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Sample records for vldl particle concentration

  1. High-fat meal effect on LDL, HDL, and VLDL particle size and number in the Genetics of Lipid-Lowering Drugs and Diet Network (GOLDN): an interventional study

    Science.gov (United States)

    Postprandial lipemia (PPL) is likely a risk factor for cardiovascular disease but these changes have not been well described and characterized in a large cohort. We assessed acute changes in the size and concentration of total and subclasses of LDL, HDL, and VLDL particles in response to a high-fat ...

  2. Genetic variants associated with VLDL, LDL and HDL particle size differ with race/ethnicity

    Science.gov (United States)

    Specific constellations of lipoprotein particle features, reflected as differences in mean lipoprotein particle diameters, are associated with risk of insulin resistance (IR) and cardiovascular disease (CVD). The associations of lipid profiles with disease risk differ by race/ethnicity, the reason f...

  3. VLDL lipolysis products increase VLDL fluidity and convert apolipoprotein E4 into a more expanded conformation.

    Science.gov (United States)

    Tetali, Sarada D; Budamagunta, Madhu S; Simion, Catalina; den Hartigh, Laura J; Kálai, Tamás; Hideg, Kálmán; Hatters, Danny M; Weisgraber, Karl H; Voss, John C; Rutledge, John C

    2010-06-01

    Our previous work indicated that apolipoprotein (apo) E4 assumes a more expanded conformation in the postprandial period. The postprandial state is characterized by increased VLDL lipolysis. In this article, we tested the hypothesis that VLDL lipolysis products increase VLDL particle fluidity, which mediates expansion of apoE4 on the VLDL particle. Plasma from healthy subjects was collected before and after a moderately high-fat meal and incubated with nitroxyl-spin labeled apoE. ApoE conformation was examined by electron paramagnetic resonance spectroscopy using targeted spin probes on cysteines introduced in the N-terminal (S76C) and C-terminal (A241C) domains. Further, we synthesized a novel nitroxyl spin-labeled cholesterol analog, which gave insight into lipoprotein particle fluidity. Our data revealed that the order of lipoprotein fluidity was HDL approximately LDL<VLDL+lipoprotein lipase. Moreover, the conformation of apoE4 depended on the lipoprotein fraction: VLDL-associated apoE4 had a more linear conformation than apoE4 associated with LDL or HDL. Further, by changing VLDL fluidity, VLDL lipolysis products significantly altered apoE4 into a more expanded conformation. Our studies indicate that after every meal, VLDL fluidity is increased causing apoE4 associated with VLDL to assume a more expanded conformation, potentially enhancing the pathogenicity of apoE4 in vascular tissue.

  4. VLDL hydrolysis by hepatic lipase regulates PPARδ transcriptional responses.

    Directory of Open Access Journals (Sweden)

    Jonathan D Brown

    Full Text Available BACKGROUND: PPARs (α,γ,δ are a family of ligand-activated transcription factors that regulate energy balance, including lipid metabolism. Despite these critical functions, the integration between specific pathways of lipid metabolism and distinct PPAR responses remains obscure. Previous work has revealed that lipolytic pathways can activate PPARs. Whether hepatic lipase (HL, an enzyme that regulates VLDL and HDL catabolism, participates in PPAR responses is unknown. METHODS/PRINCIPAL FINDINGS: Using PPAR ligand binding domain transactivation assays, we found that HL interacted with triglyceride-rich VLDL (>HDL≫LDL, IDL to activate PPARδ preferentially over PPARα or PPARγ, an effect dependent on HL catalytic activity. In cell free ligand displacement assays, VLDL hydrolysis by HL activated PPARδ in a VLDL-concentration dependent manner. Extended further, VLDL stimulation of HL-expressing HUVECs and FAO hepatoma cells increased mRNA expression of canonical PPARδ target genes, including adipocyte differentiation related protein (ADRP, angiopoietin like protein 4 and pyruvate dehydrogenase kinase-4. HL/VLDL regulated ADRP through a PPRE in the promoter region of this gene. In vivo, adenoviral-mediated hepatic HL expression in C57BL/6 mice increased hepatic ADRP mRNA levels by 30%. In ob/ob mice, a model with higher triglycerides than C57BL/6 mice, HL overexpression increased ADRP expression by 70%, demonstrating the importance of triglyceride substrate for HL-mediated PPARδ activation. Global metabolite profiling identified HL/VLDL released fatty acids including oleic acid and palmitoleic acid that were capable of recapitulating PPARδ activation and ADRP gene regulation in vitro. CONCLUSIONS: These data define a novel pathway involving HL hydrolysis of VLDL that activates PPARδ through generation of specific monounsaturated fatty acids. These data also demonstrate how integrating cell biology with metabolomic approaches provides insight

  5. Up-regulation of VLDL Receptor Expression and Its Signaling Pathway Induced by VLDL and β-VLDL

    Institute of Scientific and Technical Information of China (English)

    Zhiguo LIU; He LI; Yinghong LI; Yan WANG; Yiqiang ZONG; Youmei FENG; Zongchen FENG; Yaozu DENG; Shen QU

    2009-01-01

    Very low density lipoprotein receptor (VLDLR) is thought to participate in the patho-genesis of atherosclerosis induced by VLDL and β-VLDL. The present study was undertaken to elu-cidate the effects of VLDL and β-VLDL on VLDLR expression and its signaling pathway. RAW264.7 cells were incubated with VLDL and β-VLDL. The expression of VLDLR mRNA was detected by RT-PCR. The transcriptional activity of VLDLR gene was detected in recombinant plasmid pGL4.2VR-luciferase transfected RAW264.7. Western blot assay was used to detect the changes of phosphorylated ERK1/2 protein. Inhibitors or activators were used to observe the signal pathway in-volving VLDLR expression regulation. The results showed that VLDL and β-VLDL stimulated ERKI/2 activity in a PKC-dependent manner. VLDL or β-VLDL-induced VLDLR expression on macrophages was extremely abolished by inhibitors ERKI/2 or PKC. Our findings revealed that VLDL or β-VLDL-induced VLDLR expression via PKC/ERK cascades and the effect was linked to the transcriptional activation of VLDLR gene promoter.

  6. Effect of sepsis on VLDL kinetics: responses in basal state and during glucose infusion

    Energy Technology Data Exchange (ETDEWEB)

    Wolfe, R.R.; Shaw, J.H.; Durkot, M.J.

    1985-06-01

    The effect of gram-negative sepsis on the kinetics and oxidation of very low-density lipoprotein (VLDL) fatty acids was assessed in conscious dogs in the normal state and 24 h after infusion of live Escherichia coli. VLDL, labeled with (2-/sup 3/H)glycerol and (1-/sup 14/C)palmitic acid, was used to trace VLDL kinetics and oxidation, and (1-/sup 13/C)palmitic acid bound to albumin was infused simultaneously to quantify kinetics and oxidation of free fatty acid (FFA) in plasma. Sepsis caused a fivefold increase in the rate of VLDL production (RaVLDL). In the control dogs, the direct oxidation of VLDL-fatty acids was not an important contributor to their overall energy metabolism, but in dogs with sepsis, 17% of the total rate of CO2 production could be accounted for by VLDL-fatty acid oxidation. When glucose was infused into dogs with insulin and glucagon levels clamped at basal levels (by means of infusion of somatostatin and replacement of the hormones), RaVLDL increased significantly in the control dogs, but it did not increase further in dogs with sepsis. The authors conclude that the increase in triglyceride concentration in fasting dogs with gram-negative sepsis is the result of an increase in VLDL production and that the fatty acids in VLDL can serve as an important source of energy in sepsis.

  7. A new combined multicompartmental model for apolipoprotein B-100 and triglyceride metabolism in VLDL subfractions.

    Science.gov (United States)

    Adiels, Martin; Packard, Chris; Caslake, Muriel J; Stewart, Philip; Soro, Aino; Westerbacka, Jukka; Wennberg, Bernt; Olofsson, Sven-Olof; Taskinen, Marja-Riitta; Borén, Jan

    2005-01-01

    The use of stable isotopes in conjunction with compartmental modeling analysis has greatly facilitated studies of the metabolism of the apolipoprotein B (apoB)-containing lipoproteins in humans. The aim of this study was to develop a multicompartment model that allows us to simultaneously determine the kinetics of apoB and triglyceride (TG) in VLDL(1) and VLDL(2) after a bolus injection of [(2)H(3)]leucine and [(2)H(5)]glycerol and to follow the catabolism and transfer of the lipoprotein particles. Here, we describe the model and present the results of its application in a fasting steady-state situation in 17 subjects with lipid values representative of a Western population. Analysis of the correlations showed that plasma TG was determined by the VLDL(1) and VLDL(2) apoB and TG fractional catabolic rate. Furthermore, the model showed a linear correlation between VLDL(1) TG and apoB production. A novel observation was that VLDL TG entered the circulation within 21 min after its synthesis, whereas VLDL apoB entered the circulation after 33 min. These observations are consistent with a sequential assembly model of VLDL and suggest that the TG is added to a primordial apoB-containing particle in the liver.

  8. Tribological effects of particle concentration of an iron particle suspension

    Institute of Scientific and Technical Information of China (English)

    W.C.Leung; P.L.Wong; C.Feng; W.A.Bullough

    2001-01-01

    The general friction and wear performance of an iron particulate suspension underboundary lubrication conditions are presented. The suspension is a mixture of 1-5 micrometerdiameter carbonyl iron particles with commercial hydraulic oil, which resembles typical compositionof magneto-rheological fluids. The investigation involves changing the particle concentration of thesuspension. The optimal concentration of the suspension from a tribological view point can be ob-served from the experimental results,which provides a reference to the design of the particle load-ing of magneto-rheological fluids.

  9. Binding of β-VLDL to heparan sulfate proteoglycans requires lipoprotein lipase, whereas apoE only modulates binding affinity

    NARCIS (Netherlands)

    Beer, F. de; Hendriks, W.L.; Vark, L.C. van; Kamerling, S.W.A.; Dijk, K.W. van; Hofker, M.H.; Smelt, A.H.M.; Havekes, L.M.

    1999-01-01

    The binding of β-VLDL to heparan sulfate proteoglycans (HSPG) has been reported to be stimulated by both apoE and lipoprotein lipase (LPL). In the present study we investigated the effect of the isoform and the amount of apoE per particle, as well as the role of LPL on the binding of β-VLDL to HSPG.

  10. Interactions of Apolipoproteins AI, AII, B and HDL, LDL, VLDL with Polyurethane and Polyurethane-PEO Surfaces.

    Science.gov (United States)

    Cornelius, R M; Macri, J; Cornelius, K M; Brash, J L

    2015-11-10

    The lipoproteins (HDL, LDL, VLDL) are important components of blood present in high concentration. Surprisingly, their role in blood-biomaterial interactions has been largely ignored. In previous work apolipoprotein AI (the main protein component of HDL) was identified as a major constituent of protein layers adsorbed from plasma to biomaterials having a wide range of surface properties, and quantitative data on the adsorption of apo AI to a biomedical grade polyurethane were reported. In the present communication quantitative data on the adsorption of apo AI, apo AII and apoB (the latter being a constituent of LDL and VLDL), as well as the lipoprotein particles themselves (HDL, LDL, VLDL), to a biomedical segmented polyurethane (PU) with and without an additive containing poly(ethylene oxide) (material referred to as PEO) are reported. Using radiolabeled apo AI, apo AII, and apoB, adsorption levels on PU from buffer at a protein concentration of 50 μg/mL were found to be 0.34, 0.40, and 0.14 μg/cm(2) (12, 23, and 0.25 nmol/cm(2)) respectively. Adsorption to the PEO surface was PEO as well as to the PU surface. X-ray photoelectron spectra, following exposure of the surfaces to the lipoproteins, showed a strong phosphorus signal, confirming that adsorption had occurred. It therefore appears that a PEO-containing surface that is resistant to apolipoproteins may be less resistant to the corresponding lipoproteins.

  11. Acoustic concentration of particles in fluid flow

    Science.gov (United States)

    Ward, Michael D.; Kaduchak, Gregory

    2010-11-23

    An apparatus for acoustic concentration of particles in a fluid flow includes a substantially acoustically transparent membrane and a vibration generator that define a fluid flow path therebetween. The fluid flow path is in fluid communication with a fluid source and a fluid outlet and the vibration generator is disposed adjacent the fluid flow path and is capable of producing an acoustic field in the fluid flow path. The acoustic field produces at least one pressure minima in the fluid flow path at a predetermined location within the fluid flow path and forces predetermined particles in the fluid flow path to the at least one pressure minima.

  12. Acoustic concentration of particles in fluid flow

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Michael W.; Kaduchak, Gregory

    2017-08-15

    Disclosed herein is a acoustic concentration of particles in a fluid flow that includes a substantially acoustically transparent membrane and a vibration generator that define a fluid flow path therebetween. The fluid flow path is in fluid communication with a fluid source and a fluid outlet and the vibration generator is disposed adjacent the fluid flow path and is capable of producing an acoustic field in the fluid flow path. The acoustic field produces at least one pressure minima in the fluid flow path at a predetermined location within the fluid flow path and forces predetermined particles in the fluid flow path to the at least one pressure minima.

  13. Lipoprotein Particle Size and Concentration by Nuclear Magnetic Resonance and Incident Type 2 Diabetes in Women

    Science.gov (United States)

    Mora, Samia; Otvos, James D.; Rosenson, Robert S.; Pradhan, Aruna; Buring, Julie E.; Ridker, Paul M.

    2010-01-01

    OBJECTIVE Diabetic dyslipoproteinemia is characterized by low HDL cholesterol and high triglycerides. We examined the association of lipoprotein particle size and concentration measured by nuclear magnetic resonance (NMR) spectroscopy with clinical type 2 diabetes. RESEARCH DESIGN AND METHODS This was a prospective study of 26,836 initially healthy women followed for 13 years for incident type 2 diabetes (n = 1,687). Baseline lipids were measured directly and lipoprotein size and concentration by NMR. Cox regression models included nonlipid risk factors (age, race, smoking, exercise, education, menopause, blood pressure, BMI, family history, A1C, and C-reactive protein). NMR lipoproteins were also examined after further adjusting for standard lipids. RESULTS Incident diabetes was significantly associated with baseline HDL cholesterol, triglycerides, and NMR-measured size and concentration of LDL, IDL, HDL, and VLDL particles. The associations of these particles differed substantially by size. Small LDLNMR and small HDLNMR were positively associated with diabetes (quintile 5 vs. 1 [adjusted hazard ratios and 95% CIs], 4.04 [3.21–5.09] and 1.84 [1.54–2.19], respectively). By contrast, large LDLNMR and large HDLNMR were inversely associated (quintile 1 vs. 5, 2.50 [2.12–2.95] and 4.51 [3.68–5.52], respectively). For VLDLNMR, large particles imparted higher risk than small particles (quintile 5 vs. 1, 3.11 [2.35–4.11] and 1.31 [1.10–1.55], respectively). Lipoprotein particle size remained significant after adjusting for standard lipids and nonlipid factors. CONCLUSIONS In this prospective study of women, NMR lipoprotein size and concentrations were associated with incident type 2 diabetes and remained significant after adjustment for established risk factors, including HDL cholesterol and triglycerides. PMID:20185808

  14. Impact of phosphatidylcholine liposomes on the compositional changes of VLDL during lipoprotein lipase (LPL)-mediated lipolysis.

    Science.gov (United States)

    Ćwiklińska, Agnieszka; Gliwińska, Anna; Senderowska, Zuzanna; Kortas-Stempak, Barbara; Kuchta, Agnieszka; Dąbkowski, Kamil; Jankowski, Maciej

    2016-02-01

    Lipoprotein lipase (LPL)-mediated triacylglycerol (TAG) hydrolysis in very low density lipoprotein (VLDL) is accompanied by the release of surface material containing phospholipids (PL), free cholesterol (FC) and apolipoproteins, E (apoE) and Cs (apoCII, apoCIII). The released molecules are accepted by high density lipoprotein (HDL), and new HDL-sized apoE-containing particles are also generated. A decrease in the number of HDL particles or abnormalities in their structure is associated with unfavourable changes in the features of VLDL remnants. Phosphatidylcholine liposomes (PC-L) can also act as acceptors of surface material components released from lipoproteins. Thus, the aim of this study was to assess the impact of liposomes on compositional changes of VLDL during its LPL-mediated lipolysis. VLDL isolated from human sera was incubated with LPL (LPL:VLDLTAG; 24 μg/ml:90 mg/dl) and/or PC-L (VLDLPL:PC-LPL; 1:30 weight ratio). After incubation (2h, 37 °C) VLDL was separated from other reaction products, and VLDL lipid and apolipoprotein content were analysed. Newly generated HDL-sized apoE-containing lipoproteins were separated by two-dimensional non-denaturing gradient gel electrophoresis (2D-PAGGE). The reaction of VLDL with PC-L in the presence or absence of LPL significantly affected the VLDL composition. The ratio of core (TAG+cholesteryl ester) to surface (PL+FC) lipids in VLDL decreased 1.8-fold with PC-L, 1.2-fold with LPL and 3-fold with PC-L+LPL. The reaction with PC-L and PC-L+LPL caused a 3.7-fold and 3.2-fold decrease of apoCs/apoE average weight ratio, respectively. Compositional changes in VLDL under the influence of PC-L were accompanied by an increase in the efficiency of VLDL lipolysis and the generation of apoE-containing HDL-sized particles, heterogeneous in size (from ∼ 9 to ∼ 18.8 nm) and mobility (γ and preβ). We conclude that PL-rich particles, similarly to HDL, promote the release of surface material components from VLDL during LPL

  15. Preparation and Characterization of Polyclonal Antibodies against VLDL Receptor

    Institute of Scientific and Technical Information of China (English)

    屈伸; 陈涛; 吴凡; 尹燕华; 毕昊

    2004-01-01

    Summary: The polyclonal antibodies against VLDL receptor were prepared and identified. Rabbits were immunized with polypeptide fragment of VLDL receptor as antigen. The collected blood serum of the immunized rabbits was analyzed and identified by using ELISA and Western Blot. The results showed that the rabbit against mouse and human VLDL receptor antibodies were obtained with high titer and could recognize the natural VLDL receptors through Western blot. The prepared poly clonal antibodies against VLDL receptor provide a new tool to study the protein of VLDL receptor.

  16. Effects of insulin resistance and type 2 diabetes on lipoprotein subclass particle size and concentration determined by nuclear magnetic resonance.

    Science.gov (United States)

    Garvey, W Timothy; Kwon, Soonho; Zheng, Deyi; Shaughnessy, Sara; Wallace, Penny; Hutto, Amy; Pugh, Kimberly; Jenkins, Alicia J; Klein, Richard L; Liao, Youlian

    2003-02-01

    The insulin resistance syndrome (IRS) is associated with dyslipidemia and increased cardiovascular disease risk. A novel method for detailed analyses of lipoprotein subclass sizes and particle concentrations that uses nuclear magnetic resonance (NMR) of whole sera has become available. To define the effects of insulin resistance, we measured dyslipidemia using both NMR lipoprotein subclass analysis and conventional lipid panel, and insulin sensitivity as the maximal glucose disposal rate (GDR) during hyperinsulinemic clamps in 56 insulin sensitive (IS; mean +/- SD: GDR 15.8 +/- 2.0 mg. kg(-1). min(-1), fasting blood glucose [FBG] 4.7 +/- 0.3 mmol/l, BMI 26 +/- 5), 46 insulin resistant (IR; GDR 10.2 +/- 1.9, FBG 4.9 +/- 0.5, BMI 29 +/- 5), and 46 untreated subjects with type 2 diabetes (GDR 7.4 +/- 2.8, FBG 10.8 +/- 3.7, BMI 30 +/- 5). In the group as a whole, regression analyses with GDR showed that progressive insulin resistance was associated with an increase in VLDL size (r = -0.40) and an increase in large VLDL particle concentrations (r = -0.42), a decrease in LDL size (r = 0.42) as a result of a marked increase in small LDL particles (r = -0.34) and reduced large LDL (r = 0.34), an overall increase in the number of LDL particles (r = -0.44), and a decrease in HDL size (r = 0.41) as a result of depletion of large HDL particles (r = 0.38) and a modest increase in small HDL (r = -0.21; all P change in medium or small VLDL), which produced an increase in serum triglycerides; a decrease in LDL size as a result of an increase in small and a reduction in large LDL subclasses, plus an increase in overall LDL particle concentration, which together led to no difference (IS versus IR) or a minimal difference (IS versus diabetes) in LDL cholesterol; and a decrease in large cardioprotective HDL combined with an increase in the small HDL subclass such that there was no net significant difference in HDL cholesterol. We conclude that 1) insulin resistance had profound

  17. VLDL-activated cell signaling pathways that stimulate adrenal cell aldosterone production.

    Science.gov (United States)

    Tsai, Ying-Ying; Rainey, William E; Johnson, Maribeth H; Bollag, Wendy B

    2016-09-15

    Aldosterone plays an important role in regulating ion and fluid homeostasis and thus blood pressure, and hyperaldosteronism results in hypertension. Hypertension is also observed with obesity, which is associated with additional health risks, including cardiovascular disease. Obese individuals have high serum levels of very low-density lipoprotein (VLDL), which has been shown to stimulate aldosterone production; however, the mechanisms underlying VLDL-induced aldosterone production are still unclear. Here we demonstrate in human adrenocortical carcinoma (HAC15) cells that submaximal concentrations of angiotensin II and VLDL stimulate aldosterone production in an additive fashion, suggesting the possibility of common mechanisms of action. We show using inhibitors that VLDL-induced aldosterone production is mediated by the PLC/IP3/PKC signaling pathway. Our results suggest that PKC is upstream of the extracellular signal-regulated kinase (ERK) activation previously observed with VLDL. An understanding of the mechanisms mediating VLDL-induced aldosterone production may provide insights into therapies to treat obesity-associated hypertension.

  18. Comparison of FTIR-ATR and Raman spectroscopy in determination of VLDL triglycerides in blood serum with PLS regression

    Science.gov (United States)

    Oleszko, Adam; Hartwich, Jadwiga; Wójtowicz, Anna; Gąsior-Głogowska, Marlena; Huras, Hubert; Komorowska, Małgorzata

    2017-08-01

    Hypertriglyceridemia, related with triglyceride (TG) in plasma above 1.7 mmol/L is one of the cardiovascular risk factors. Very low density lipoproteins (VLDL) are the main TG carriers. Despite being time consuming, demanding well-qualified staff and expensive instrumentation, ultracentrifugation technique still remains the gold standard for the VLDL isolation. Therefore faster and simpler method of VLDL-TG determination is needed. Vibrational spectroscopy, including FT-IR and Raman, is widely used technique in lipid and protein research. The aim of this study was assessment of Raman and FT-IR spectroscopy in determination of VLDL-TG directly in serum with the isolation step omitted. TG concentration in serum and in ultracentrifugated VLDL fractions from 32 patients were measured with reference colorimetric method. FT-IR and Raman spectra of VLDL and serum samples were acquired. Partial least square (PLS) regression was used for calibration and leave-one-out cross validation. Our results confirmed possibility of reagent-free determination of VLDL-TG directly in serum with both Raman and FT-IR spectroscopy. Quantitative VLDL testing by FT-IR and/or Raman spectroscopy applied directly to maternal serum seems to be promising screening test to identify women with increased risk of adverse pregnancy outcomes and patient friendly method of choice based on ease of performance, accuracy and efficiency.

  19. Effects of atorvastatin and n-3 fatty acid supplementation on VLDL apolipoprotein C-III kinetics in men with abdominal obesity.

    Science.gov (United States)

    Chan, Dick C; Nguyen, Minh N; Watts, Gerald F; Ooi, Esther Mm; Barrett, P Hugh R

    2010-04-01

    Disturbed apolipoprotein (apo) C-III metabolism in obese subjects may account for hypertriglyceridemia and increased risk of cardiovascular disease. Atorvastatin and fish oils decrease plasma triglycerides and VLDL concentrations, but the underlying mechanisms are not fully understood. We studied the independent and combined effects of atorvastatin and fish oils on the metabolism of VLDL apo C-III in obese men. We carried out a 6-wk randomized, placebo-controlled, 2 x 2 factorial intervention study of atorvastatin (40 mg/d) and fish oils (4 g/d) on VLDL apo C-III kinetics in the postabsorptive state in 39 abdominally obese men using intravenous administration of d(3)-leucine. VLDL apo C-III isotopic enrichments were measured by using gas chromatography-mass spectrometry with kinetic parameters derived by using a multicompartmental model. Atorvastatin significantly (P triglycerides but did not significantly alter plasma VLDL apo C-III concentrations or kinetic parameters. Combination treatment provided no additional effect on VLDL apo C-III concentrations or kinetics compared with atorvastatin alone. In obesity, the triglyceride-lowering effect of atorvastatin, but not fish oils, is associated with increased VLDL apo C-III fractional catabolism and hence lower VLDL apo C-III concentrations. Combination treatment provided no significant additional improvement in VLDL apo C-III metabolism compared with atorvastatin alone.

  20. Overproduction of altered VLDL in an insulin-resistance rat model: Influence of SREBP-1c and PPAR-α.

    Science.gov (United States)

    Lucero, Diego; Miksztowicz, Verónica; Macri, Vanesa; López, Gustavo H; Friedman, Silvia; Berg, Gabriela; Zago, Valeria; Schreier, Laura

    2015-01-01

    In insulin-resistance, VLDL presents alterations that increase its atherogenic potential. The mechanism by which insulin-resistance promotes the production of altered VLDL is still not completely understood. The aim of this study was to evaluate the relationship between the expression of sterol regulatory element binding protein 1c (SREBP-1c) and of peroxisome proliferator-activated receptor-α (PPAR-α), with the features of composition and size of VLDL in an insulin-resistance rat model induced by a sucrose rich diet (SRD). The study was conducted on 12 male Wistar rats (180g) receiving SRD (12 weeks) and 12 controls. Lipid profile, free fatty acids, glucose, and insulin were measured. Lipid content in liver and visceral fat were assessed. Isolated VLDL (d<1.006g/ml) was characterized by its chemical composition and size by HPLC. The respective hepatic expression of SREBP-1c and PPAR-α was determined (Western blot). As expected, SRD had elevated triglycerides (TG), free fatty acids and insulin levels, and decreased HDL-cholesterol (p<0.05), together with augmented hepatic and visceral fat (p<0.05). SRD showed higher VLDL total mass - with increased TG content - and predominance of large VLDL (p<0.05). SRD showed an increase in SREBP-1c (precursor and mature forms) and decreased PPAR-α expression (p<0.045). SREBP-1c forms were positively associated with VLDL total mass (p<0.04), VLDL-TG% (p<0.019), and large VLDL% (p<0.002). On the other hand, PPAR-α correlated negatively with VLDL total mass (p=0.05), VLDL-TG% (p=0.005), and large VLDL% (p=0.002). Insulin-resistance, by coordinated activation of SREBP-1c and reduction of PPAR-α, could promote the secretion of larger and TG over-enriched VLDL particles, with greater atherogenic capacity. Copyright © 2014 Sociedad Española de Arteriosclerosis. Published by Elsevier España. All rights reserved.

  1. System for particle concentration and detection

    Science.gov (United States)

    Morales, Alfredo M.; Whaley, Josh A.; Zimmerman, Mark D.; Renzi, Ronald F.; Tran, Huu M.; Maurer, Scott M.; Munslow, William D.

    2013-03-19

    A new microfluidic system comprising an automated prototype insulator-based dielectrophoresis (iDEP) triggering microfluidic device for pathogen monitoring that can eventually be run outside the laboratory in a real world environment has been used to demonstrate the feasibility of automated trapping and detection of particles. The system broadly comprised an aerosol collector for collecting air-borne particles, an iDEP chip within which to temporarily trap the collected particles and a laser and fluorescence detector with which to induce a fluorescence signal and detect a change in that signal as particles are trapped within the iDEP chip.

  2. Nutritional repletion of children with severe acute malnutrition does not affect VLDL apolipoprotein B-100 synthesis rate.

    Science.gov (United States)

    Badaloo, Asha V; Forrester, Terrence; Reid, Marvin; Jahoor, Farook

    2012-05-01

    VLDL apo B-100 is essential for the secretion of liver fat. It is thought that synthesis of this lipoprotein is impaired in childhood severe acute malnutrition (SAM), especially in the edematous syndromes, and that this contributes to the common occurrence of hepatic steatosis in this condition. However, to our knowledge, it has not been confirmed that VLDL apo B-100 synthesis is slower in edematous compared with nonedematous SAM and that it is impaired in the malnourished compared with the well-nourished state. Therefore, VLDL apo B-100 kinetics were measured in 2 groups of children with SAM (15 edematous and 7 nonedematous), aged 4-20 mo, at 3 stages during treatment. Measurements were done at 4 ± 1 d postadmission, mid- catch-up growth in weight, and at recovery (normal weight-for-length). VLDL apo B-100 synthesis was determined using stable isotope methodology to measure the rate of incorporation of (2)H(3)-leucine into its apoprotein moiety. The fractional and absolute synthesis of VLDL apo B-100 did not differ between the groups or from the initial malnourished stage to the recovery stage. Concentrations of VLDL apo B-100 were greater in the edematous than in the nonedematous group (P < 0.04) and did not differ from the initial stage to recovery. The data indicate that VLDL apo B-100 synthesis is not reduced when children develop either edematous or nonedematous SAM.

  3. On the concentration properties of Interacting particle processes

    CERN Document Server

    Del Moral, Pierre; Wu, Liming

    2011-01-01

    These lecture notes present some new concentration inequalities for Feynman-Kac particle processes. We analyze different types of stochastic particle models, including particle profile occupation measures, genealogical tree based evolution models, particle free energies, as well as backward Markov chain particle models. We illustrate these results with a series of topics related to computational physics and biology, stochastic optimization, signal processing and bayesian statistics, and many other probabilistic machine learning algorithms. Special emphasis is given to the stochastic modeling and the quantitative performance analysis of a series of advanced Monte Carlo methods, including particle filters, genetic type island models, Markov bridge models, interacting particle Markov chain Monte Carlo methodologies.

  4. Particle size- and concentration-dependent separation of magnetic nanoparticles

    Science.gov (United States)

    Witte, Kerstin; Müller, Knut; Grüttner, Cordula; Westphal, Fritz; Johansson, Christer

    2017-04-01

    Small magnetic nanoparticles with a narrow size distribution are of great interest for several biomedical applications. When the size of the particles decreases, the magnetic moment of the particles decreases. This leads to a significant increase in the separation time by several orders of magnitude. Therefore, in the present study the separation processes of bionized nanoferrites (BNF) with different sizes and concentrations were investigated with the commercial Sepmag Q system. It was found that an increasing initial particle concentration leads to a reduction of the separation time for large nanoparticles due to the higher probability of building chains. Small nanoparticles showed exactly the opposite behavior with rising particle concentration up to 0.1 mg(Fe)/ml. For higher iron concentrations the separation time remains constant and the measured Z-average decreases in the supernatant at same time intervals. At half separation time a high yield with decreasing hydrodynamic diameter of particles can be obtained using higher initial particle concentrations.

  5. Brownian coagulation at high particle concentrations

    NARCIS (Netherlands)

    Trzeciak, T. M.

    2012-01-01

    The process of Brownian coagulation, whereby particles are brought together by thermal motion and grow by collisions, is one of the most fundamental processes influencing the final properties of particulate matter in a variety of technically important systems. It is of importance in colloids, emulsi

  6. Numerical Simulation of Particle Concentration in a Gas Cyclone Separator

    Institute of Scientific and Technical Information of China (English)

    Xue Xiaohu; Sun Guogang; Wan Gujun; Shi Mingxian

    2007-01-01

    The particle concentration inside a cyclone separator at different operation parameters was simulated with the FLUENT software. The Advanced Reynolds Stress Model (ARSM) was used in gas phase turbulence modeling.Stochastic Particle Tracking Model (SPTM) and the Particle-Source-In-Cell (PSIC) method were adopted for particles computing. The interaction between particles and the gas phase was also taken into account. The numerical simulation results were in agreement with the experimental data. The simulation revealed that an unsteady spiral dust strand appeared near the cyclone wall and a non-axi-symmetrical dust ring appeared in the annular space and under the cover plate of the cyclone. There were two regions in the radial particle concentration distribution, in which particle concentration was low in the inner region (r/R≤0.75) and increased greatly in the outer region (r/R>0.75). Large particles generally had higher concentration in the near-wall region and small particles had higher concentration in the inner swirling flow region. The axial distribution of particle concentration in the inner swirling flow (r/R≤0.3) region showed that there existed serious fine particle entrainment within the height of 0.5D above the dust discharge port and a short-cut flow at a distance of about 0.25D below the entrance of the vortex finder. The dimensionless concentration in the high-concentration region increased obviously in the upper part of the cyclone separation space when inlet particle loading was large. With increasing gas temperature, the particle separation ability of the cyclone was obviously weakened.

  7. Effects of fish oil on oxidation resistance of VLDL in hypertriglyceridemic patients

    NARCIS (Netherlands)

    Hau, M.-F.; Smelt, A.H.M.; Bindels, A.J.G.H.; Sijbrands, E.J.G.; Laarse, A. van der; Onkenhout, W.; Duyvenvoorde, W. van; Princen, H.M.G.

    1996-01-01

    In hypertriglyceridemic (HTG) patients the addition of fish oil to the diet causes a marked reduction in the concentration of triglyceride-rich lipoproteins in the serum. To investigate the effects of fish oil on the oxidation resistance of VLDL and LDL in HTG patients, nine male patients received 1

  8. Effects of fish oil on oxidation resistance of VLDL in hypertriglyceridemic patients

    NARCIS (Netherlands)

    Hau, M.-F.; Smelt, A.H.M.; Bindels, A.J.G.H.; Sijbrands, E.J.G.; Laarse, A. van der; Onkenhout, W.; Duyvenvoorde, W. van; Princen, H.M.G.

    1996-01-01

    In hypertriglyceridemic (HTG) patients the addition of fish oil to the diet causes a marked reduction in the concentration of triglyceride-rich lipoproteins in the serum. To investigate the effects of fish oil on the oxidation resistance of VLDL and LDL in HTG patients, nine male patients received 1

  9. Lipoprotein particle distribution and skeletal muscle lipoprotein lipase activity after acute exercise

    Directory of Open Access Journals (Sweden)

    Harrison Michael

    2012-07-01

    Full Text Available Abstract Background Many of the metabolic effects of exercise are due to the most recent exercise session. With recent advances in nuclear magnetic resonance spectroscopy (NMRS, it is possible to gain insight about which lipoprotein particles are responsible for mediating exercise effects. Methods Using a randomized cross-over design, very low density lipoprotein (VLDL responses were evaluated in eight men on the morning after i an inactive control trial (CON, ii exercising vigorously on the prior evening for 100 min followed by fasting overnight to maintain an energy and carbohydrate deficit (EX-DEF, and iii after the same exercise session followed by carbohydrate intake to restore muscle glycogen and carbohydrate balance (EX-BAL. Results The intermediate, low and high density lipoprotein particle concentrations did not differ between trials. Fasting triglyceride (TG determined biochemically, and mean VLDL size were lower in EX-DEF but not in EX-BAL compared to CON, primarily due to a reduction in VLDL-TG in the 70–120 nm (large particle range. In contrast, VLDL-TG was lower in both EX-DEF and EX-BAL compared to CON in the 43–55 nm (medium particle range. VLDL-TG in smaller particles (29–43 nm was unaffected by exercise. Because the majority of VLDL particles were in this smallest size range and resistant to change, total VLDL particle concentration was not different between any of these conditions. Skeletal muscle lipoprotein lipase (LPL activity was also not different across these 3 trials. However, in CON only, the inter-individual differences in LPL activity were inversely correlated with fasting TG, VLDL-TG, total, large and small VLDL particle concentration and VLDL size, indicating a regulatory role for LPL in the non-exercised state. Conclusions These findings reveal a high level of differential regulation between different sized triglyceride-rich lipoproteins following exercise and feeding, in the absence of changes in

  10. Lipoprotein particle distribution and skeletal muscle lipoprotein lipase activity after acute exercise

    LENUS (Irish Health Repository)

    Harrison, Michael

    2012-06-06

    AbstractBackgroundMany of the metabolic effects of exercise are due to the most recent exercise session. With recent advances in nuclear magnetic resonance spectroscopy (NMRS), it is possible to gain insight about which lipoprotein particles are responsible for mediating exercise effects.MethodsUsing a randomized cross-over design, very low density lipoprotein (VLDL) responses were evaluated in eight men on the morning after i) an inactive control trial (CON), ii) exercising vigorously on the prior evening for 100 min followed by fasting overnight to maintain an energy and carbohydrate deficit (EX-DEF), and iii) after the same exercise session followed by carbohydrate intake to restore muscle glycogen and carbohydrate balance (EX-BAL).ResultsThe intermediate, low and high density lipoprotein particle concentrations did not differ between trials. Fasting triglyceride (TG) determined biochemically, and mean VLDL size were lower in EX-DEF but not in EX-BAL compared to CON, primarily due to a reduction in VLDL-TG in the 70–120 nm (large) particle range. In contrast, VLDL-TG was lower in both EX-DEF and EX-BAL compared to CON in the 43–55 nm (medium) particle range. VLDL-TG in smaller particles (29–43 nm) was unaffected by exercise. Because the majority of VLDL particles were in this smallest size range and resistant to change, total VLDL particle concentration was not different between any of these conditions. Skeletal muscle lipoprotein lipase (LPL) activity was also not different across these 3 trials. However, in CON only, the inter-individual differences in LPL activity were inversely correlated with fasting TG, VLDL-TG, total, large and small VLDL particle concentration and VLDL size, indicating a regulatory role for LPL in the non-exercised state.ConclusionsThese findings reveal a high level of differential regulation between different sized triglyceride-rich lipoproteins following exercise and feeding, in the absence of changes in LPL activity.

  11. THEORETICAL ANALYSIS ON THE VERTICAL DISTRIBUTION OF PARTICLE CONCENTRATION

    Institute of Scientific and Technical Information of China (English)

    Guangqian WANG; Xudong FU

    2001-01-01

    In steady, solid-liquid two-phase turbulent flows, there exist two typical patterns of the vertical distribution of particle concentration. The pattern I shows a maximum concentration at an elevation above the bed. The pattern II shows an increase of the particle concentration downward over the whole vertical,with the maximum at the bed. Most of the theories on particle concentration distribution have been done with the pattern II, and it is lack of a successful theory coveting both of the two patterns. This paper reviews the particle distribution theories, including the diffusion theory, the mixture theory, the energy theory, the similarity theory, the stochastic theory and the kinetic theory. The kinetic theory is also applied to describe the vertical distribution of particle concentration in both dilute and dense flows.

  12. Pollutant Ground Concentrations of Nonneutrally Buoyant Particles.

    Science.gov (United States)

    Mandel, Alon; Stern, Eli; Ullmann, Amos; Brauner, Neima

    2017-03-23

    A methodology is suggested for the estimation of the mass density and the cumulative ground deposition of a nonvolatile, nonneutrally buoyant, air pollutant (liquid or solid) released from a polluted column (following an explosion caused during routine operation in, e.g., the chemical industry or due to any kind of hostile act) and deposited on the ground via gravitational settling. In many cases, the deposited mass due to gravitational settling constitutes a significant fraction of the original inventory released from the source. Implementation of the methodology in preliminary risk assessments can serve as an efficient tool for emergency planning for both immediate and long-term measures such as evacuation and decontamination. The methodology considers, inter alia, an estimation of the critical particle diameter, particle size, and mass distributions along the polluted column. This methodology was developed to apply in rural regions since proper application of relevant meteorological input data can be accomplished mainly for such areas. © 2017 Society for Risk Analysis.

  13. Impact of particle formation on atmospheric ions and particle number concentrations in an urban environment

    Science.gov (United States)

    Cheung, H. C.; Chou, C. C.-K.; Jayaratne, E. R.; Morawska, L.

    2015-04-01

    A measurement campaign was conducted from 3 to 19 December 2012 at an urban site of Brisbane, Australia. Size distribution of ions and particle number concentrations were measured to investigate the influence of particle formation and biomass burning on atmospheric ion and particle concentrations. Overall ion and particle number concentrations during the measurement period were found to be (- 1.2 × 103 cm- 3 | + 1.6 × 103 cm- 3) and 4.4 × 103, respectively. The results of correlation analysis between concentrations of ions and nitrogen oxides indicated that positive and negative ions originated from similar sources, and that vehicle exhaust emissions had a more significant influence on intermediate/large ions, while cluster ions rapidly attached to larger particles once emitted into the atmosphere. Diurnal variations in ion concentration suggested the enrichment of intermediate and large ions on new particle formation event days, indicating that they were involved in the particle formation processes. Elevated total ions, particularly larger ions, and particle number concentrations were found during biomass burning episodes. This could be due to the attachment of cluster ions onto accumulation mode particles or production of charged particles from biomass burning, which were in turn transported to the measurement site. The results of this work enhance scientific understanding of the sources of atmospheric ions in an urban environment, as well as their interactions with particles during particle formation processes.

  14. Concentrated whey protein particle dispersions: Heat stability and rheological properties

    NARCIS (Netherlands)

    Saglam, D.; Venema, P.; Vries, de R.J.; Shi, J.; Linden, van der E.

    2013-01-01

    In this work heat stability and rheological properties of concentrated whey protein particle dispersions in different dispersing media are studied. Whey protein particles (protein content ~20% w/v) having an average size of a few microns were formed using a combination of two-step emulsification and

  15. Saharan Dust Particle Size And Concentration Distribution In Central Ghana

    Science.gov (United States)

    Sunnu, A. K.

    2010-12-01

    A.K. Sunnu*, G. M. Afeti* and F. Resch+ *Department of Mechanical Engineering, Kwame Nkrumah University of Science and Technology (KNUST) Kumasi, Ghana. E-mail: albertsunnu@yahoo.com +Laboratoire Lepi, ISITV-Université du Sud Toulon-Var, 83162 La Valette cedex, France E-mail: resch@univ-tln.fr Keywords: Atmospheric aerosol; Saharan dust; Particle size distributions; Particle concentrations. Abstract The Saharan dust that is transported and deposited over many countries in the West African atmospheric environment (5°N), every year, during the months of November to March, known locally as the Harmattan season, have been studied over a 13-year period, between 1996 and 2009, using a location at Kumasi in central Ghana (6° 40'N, 1° 34'W) as the reference geographical point. The suspended Saharan dust particles were sampled by an optical particle counter, and the particle size distributions and concentrations were analysed. The counter gives the total dust loads as number of particles per unit volume of air. The optical particle counter used did not discriminate the smoke fractions (due to spontaneous bush fires during the dry season) from the Saharan dust. Within the particle size range measured (0.5 μm-25 μm.), the average inter-annual mean particle diameter, number and mass concentrations during the northern winter months of January and February were determined. The average daily number concentrations ranged from 15 particles/cm3 to 63 particles/cm3 with an average of 31 particles/cm3. The average daily mass concentrations ranged from 122 μg/m3 to 1344 μg/m3 with an average of 532 μg/m3. The measured particle concentrations outside the winter period were consistently less than 10 cm-3. The overall dust mean particle diameter, analyzed from the peak representative Harmattan periods over the 13-year period, ranged from 0.89 μm to 2.43 μm with an average of 1.5 μm ± 0.5. The particle size distributions exhibited the typical distribution pattern for

  16. Optical sensor technology for simultaneous measurement of particle speed and concentration of micro sized particles

    DEFF Research Database (Denmark)

    Clausen, Casper; Han, Anpan; Kristensen, Martin

    2013-01-01

    Experimental characterization of a sensor technology that can measure particle speed and concentration simultaneously in liquids and gases is presented here. The basic sensor principle is based on an optical element that shapes a light beam into well-defined fringes. The technology can be described...... independently from particle speeds and is a key advantage compared to normal Laser Particle Counters....

  17. Intercomparison of number concentration measurements by various aerosol particle counters

    Science.gov (United States)

    Ankilov, A.; Baklanov, A.; Colhoun, M.; Enderle, K.-H.; Gras, J.; Julanov, Yu.; Kaller, D.; Lindner, A.; Lushnikov, A. A.; Mavliev, R.; McGovern, F.; Mirme, A.; O'Connor, T. C.; Podzimek, J.; Preining, O.; Reischl, G. P.; Rudolf, R.; Sem, G. J.; Szymanski, W. W.; Tamm, E.; Vrtala, A. E.; Wagner, P. E.; Winklmayr, W.; Zagaynov, V.

    Total aerosol particle number concentrations, as measured by means of 16 different measurement systems, have been quantitatively compared during an international workshop at the Institute for Experimental Physics of the University of Vienna, Austria, which was coordinated within the Committee on Nucleation and Atmospheric Aerosols (ICCP-IUGG). The range of measuring instruments includes Pollak counters (PCO) in use already for several decades, presently available commercial particle counters, as well as laboratory prototypes. The operation of the instruments considered was based on different measurement principles: (1) adiabatic expansion condensation particle counter, (2) flow diffusion condensation particle counter, (3) turbulent mixing condensation particle counter, (4) laser optical particle counter, and (5) electrostatic particle measurement system. Well-defined test aerosols with various chemical compositions were considered: DEHS, sodium chloride, silver, hydrocarbons, and tungsten oxide. The test aerosols were nearly monodispersed with mean particle diameters between 4 and 520 nm, the particle number concentrations were varied over a range from about 4×10 1 to 7×10 6 cm -3. A few measurements were performed with two-component aerosol mixtures. For simultaneous concentration measurements, the various instruments considered were operated under steady state conditions in a linear flow system. A series of at least 10 single concentration measurements was performed by each individual instrument at each set of test aerosol parameters. The average of the concentration data measured by the various instruments was defined as a common reference. The number concentrations obtained from the various instruments typically agreed within a factor of about two over the entire concentration range considered. The agreement of the measured concentrations is notable considering the various different measurement principles applied in this study, and particularly in view of the

  18. Particle Number Concentrations for HI-SCALE Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Hering, Susanne V [Aerosol Dynamics, Inc.

    2016-06-01

    In support of the Holistic Interactions of Shallow Clouds, Aerosols, and Ecosystems (HI-SCALE) project to study new particle formation in the atmosphere, a pair of custom water condensation particle counters were provided to the second intensive field campaign, from mid-August through mid-September 2017, at the U.S. Department of Energy Southern Great Plains Atmospheric Radiation Measurement (ARM) Climate Research Facility observatory. These custom instruments were developed by Aerosol Dynamics, Inc. (Hering et al. 2017) to detect particles into the nanometer size range. Referred to as “versatile water condensation particle counter (vWCPC)”, they are water-based, laminar-flow condensational growth instruments whose lower particle size threshold can be set based on user-selected operating temperatures. For HI-SCALE, the vWCPCs were configured to measure airborne particle number concentrations in the size range from approximately 2nm to 2μm. Both were installed in the particle sizing system operated by Chongai Kuang of Brookhaven National Laboratory (BNL). One of these was operated in parallel to a TSI Model 3776, upstream of the mobility particle sizing system, to measure total ambient particle concentrations. The airborne particle concentration data from this “total particle number vWCPC” (Ntot-vWCPC) system has been reported to the ARM database. The data are reported with one-second resolution. The second vWCPC was operated in parallel with the BNL diethylene glycol instrument to count particles downstream of a separate differential mobility size analyzer. Data from this “DMA-vWCPC” system was logged by BNL, and will eventually be provided by that laboratory.

  19. Particle sedimentation monitoring in high-concentration slurries

    Science.gov (United States)

    Nagasawa, Yoshihiro; Kato, Zenji; Tanaka, Satoshi

    2016-11-01

    In this study, the sedimentation states of particles in high-concentration slurries were elucidated by monitoring their internal states. We prepared transparent high-concentration silica slurries by adjusting the refractive index of the aqueous glycerol liquid in which the particles were dispersed to match that of the silica particles. In addition, a fluorescent dye was dissolved in the liquid. Then, we directly observed the individual and flocculated particles in the slurries during sedimentation by confocal laser scanning fluorescent microscopy. The particles were found to sediment very slowly while exhibiting fluctuating motion. The particle sedimentation rate in the high-concentration slurry with the aqueous glycerol solution (η =0.068 Pa. s ) and a particle volume fraction on the order of 0.3 was determined to be 1.58 ± 0.66 μ m. min-1 on the basis of the obtained image sequences for 24.9 h. In-situ observation provides a large amount of information about the sedimentation behavior of particles in condensed matter.

  20. Aspirin reduces hypertriglyceridemia by lowering VLDL-triglyceride production in mice fed a high-fat diet.

    Science.gov (United States)

    van Diepen, Janna A; Vroegrijk, Irene O C M; Berbée, Jimmy F P; Shoelson, Steven E; Romijn, Johannes A; Havekes, Louis M; Rensen, Patrick C N; Voshol, Peter J

    2011-12-01

    Systemic inflammation is strongly involved in the pathophysiology of the metabolic syndrome, a cluster of metabolic risk factors that includes hypertriglyceridemia. Aspirin treatment lowers inflammation via inhibition of NF-κB activity but also reduces hypertriglyceridemia in humans. The aim of this study was to investigate the mechanism by which aspirin improves hypertriglyceridemia. Human apolipoprotein CI (apoCI)-expressing mice (APOC1 mice), an animal model with elevated plasma triglyceride (TG) levels, as well as normolipidemic wild-type (WT) mice were fed a high-fat diet (HFD) and treated with aspirin. Aspirin treatment reduced hepatic NF-κB activity in HFD-fed APOC1 and WT mice, and in addition, aspirin decreased plasma TG levels (-32%, P < 0.05) in hypertriglyceridemic APOC1 mice. This TG-lowering effect could not be explained by enhanced VLDL-TG clearance, but aspirin selectively reduced hepatic production of VLDL-TG in both APOC1 (-28%, P < 0.05) and WT mice (-33%, P < 0.05) without affecting VLDL-apoB production. Aspirin did not alter hepatic expression of genes involved in FA oxidation, lipogenesis, and VLDL production but decreased the incorporation of plasma-derived FA by the liver into VLDL-TG (-24%, P < 0.05), which was independent of hepatic expression of genes involved in FA uptake and transport. We conclude that aspirin improves hypertriglyceridemia by decreasing VLDL-TG production without affecting VLDL particle production. Therefore, the inhibition of inflammatory pathways by aspirin could be an interesting target for the treatment of hypertriglyceridemia.

  1. Preferential concentration of heavy particles in compressible isotropic turbulence

    Science.gov (United States)

    Zhang, Qingqing; Liu, Han; Ma, Zongqiang; Xiao, Zuoli

    2016-05-01

    Numerical simulations of particle-laden compressible isotropic turbulence with Taylor Reynolds number Reλ ˜ 100 are conducted by using a high-order turbulence solver, which is based on high-order compact finite difference method in the whole flow domain and localized artificial diffusivities for discontinuities. For simplicity, only one-way coupling (i.e., the influence of fluid on particles) between the carrier flow and particles is considered. The focus is on the study of the preferential concentration of heavy particles in dissipative scale of turbulence and the underlying mechanisms. Firstly, the effect of Stokes number (St) on the particle distribution in flow of Mach 1.01 (referred to as high-Mach-number case in this study) is investigated as a necessary supplementation for the previous studies in incompressible and weakly compressible flows. It turns out that heavy particles with Stokes number close to unity exhibit the strongest preferential concentration, which is in agreement with the observation in incompressible flow. All types of heavy particles have a tendency to accumulate in high-density regions of the background flow. While all kinds of particles dominantly collect in low-vorticity regions, intermediate and large particles (St = 1 and St = 5) are also found to collect in high-vorticity regions behind the randomly formed shocklets. Secondly, the impact of turbulent Mach number (Mt) (or the compressibility) of the carrier flow on the spatial distribution of the particles with St = 1 is discussed using the simulated compressible flows with Mt being 0.22, 0.68, and 1.01, respectively. In low-Mach-number flow, particles tend to concentrate in regions of low vorticity due to the centrifuge effect of vortices and particle concentration decreases monotonically with the increasing vorticity magnitude. As Mach number increases, the degree of particle clustering is slightly weakened in low-vorticity regions but is enhanced in high-vorticity regions, which

  2. Preferrential Concentration of Particles in Protoplanetary Nebula Turbulence

    Science.gov (United States)

    Hartlep, Thomas; Cuzzi, Jeffrey N.

    2015-01-01

    Preferential concentration in turbulence is a process that causes inertial particles to cluster in regions of high strain (in-between high vorticity regions), with specifics depending on their stopping time or Stokes number. This process is thought to be of importance in various problems including cloud droplet formation and aerosol transport in the atmosphere, sprays, and also in the formation of asteroids and comets in protoplanetary nebulae. In protoplanetary nebulae, the initial accretion of primitive bodies from freely-floating particles remains a problematic subject. Traditional growth-by-sticking models encounter a formidable "meter-size barrier" [1] in turbulent nebulae. One scenario that can lead directly from independent nebula particulates to large objects, avoiding the problematic m-km size range, involves formation of dense clumps of aerodynamically selected, typically mm-size particles in protoplanetary turbulence. There is evidence that at least the ordinary chondrite parent bodies were initially composed entirely of a homogeneous mix of such particles generally known as "chondrules" [2]. Thus, while it is arcane, turbulent preferential concentration acting directly on chondrule size particles are worthy of deeper study. Here, we present the statistical determination of particle multiplier distributions from numerical simulations of particle-laden isotopic turbulence, and a cascade model for modeling turbulent concentration at lengthscales and Reynolds numbers not accessible by numerical simulations. We find that the multiplier distributions are scale dependent at the very largest scales but have scale-invariant properties under a particular variable normalization at smaller scales.

  3. An Analysis of Electrophoresis of Concentrated Suspensions of Colloidal Particles.

    Science.gov (United States)

    Johnson; Davis

    1999-07-15

    An analysis of the electrophoretic motion of charged colloidal particles in a concentrated suspension is developed to predict the electrophoretic mobility of the particles and the electrical conductivity of the suspension. The analysis is based on a unit cell model that takes into account particle-particle hydrodynamic interactions and includes relatively thick electric double layers. The fluid motion in the unit cell is treated by writing the relevant Navier-Stokes equation in terms of the stream function and vorticity. The governing equations were then solved by a finite-difference method. The calculated electrophoretic mobilities are in agreement with prior analytical solutions for moderately concentrated suspensions, and the theory reduces to the result of O'Brien and White for low to moderate zeta potentials and dilute suspensions and to the classical result of Smoluchowski for thin double layers and dilute suspensions. A parametric study shows that the electrical conductivity of the suspension relative to a free electrolyte solution is affected by the counterion to co-ion diffusivity ratio, the double-layer thickness, and the volume fraction of particles. For a dispersion of moderately charged particles (moderate zeta potentials) with thick double layers, the numerical model predicts the electrical conductivity in agreement with experimental values reported in the literature. Copyright 1999 Academic Press.

  4. System for concentrating and analyzing particles suspended in a fluid

    Science.gov (United States)

    Fiechtner, Gregory J [Bethesda, MD; Cummings, Eric B [Livermore, CA; Singh, Anup K [Danville, CA

    2011-04-26

    Disclosed is a device for separating and concentrating particles suspended in a fluid stream by using dielectrophoresis (DEP) to trap and/or deflect those particles as they migrate through a fluid channel. The method uses fluid channels designed to constrain a liquid flowing through it to uniform electrokinetic flow velocities. This behavior is achieved by connecting deep and shallow sections of channels, with the channel depth varying abruptly along an interface. By careful design of abrupt changes in specific permeability at the interface, an abrupt and spatially uniform change in electrokinetic force can be selected. Because these abrupt interfaces also cause a sharp gradient in applied electric fields, a DEP force also can be established along the interface. Depending on the complex conductivity of the suspended particles and the immersion liquid, the DEP force can controllably complement or oppose the local electrokinetic force transporting the fluid through the channel allowing for manipulation of particles suspended in the transporting liquid.

  5. Outdoor ultrafine particle concentrations in front of fast food restaurants

    NARCIS (Netherlands)

    Vert, Cristina; Meliefste, Kees; Hoek, Gerard

    2016-01-01

    Ultrafine particles (UFPs) have been associated with negative effects on human health. Emissions from motor vehicles are the principal source of UFPs in urban air. A study in Vancouver suggested that UFP concentrations were related to density of fast food restaurants near the monitoring sites. A pre

  6. Forecasting ultrafine particle concentrations from satellite and in situ observations

    Science.gov (United States)

    Crippa, P.; Castruccio, S.; Pryor, S. C.

    2017-02-01

    Recent innovations in remote sensing technologies and retrievals offer the potential for predicting ultrafine particle (UFP) concentrations from space. However, the use of satellite observations to provide predictions of near-surface UFP concentrations is limited by the high frequency of incomplete predictor values (due to missing observations), the lack of models that account for the temporal dependence of UFP concentrations, and the large uncertainty in satellite retrievals. Herein we present a novel statistical approach designed to address the first two limitations. We estimate UFP concentrations by using lagged estimates of UFP and concurrent satellite-based observations of aerosol optical properties, ultraviolet solar radiation flux, and trace gas concentrations, wherein an expectation maximization algorithm is used to impute missing values in the satellite observations. The resulting model of UFP (derived by using an autoregressive moving average model with exogenous inputs) explains 51 and 28% of the day-to-day variability in concentrations at two sites in eastern North America.

  7. Increased hepatic VLDL secretion, lipogenesis, and SREBP-1 expression in the corpulent JCR:LA-cp rat.

    Science.gov (United States)

    Elam, M B; Wilcox, H G; Cagen, L M; Deng, X; Raghow, R; Kumar, P; Heimberg, M; Russell, J C

    2001-12-01

    The corpulent JCR:LA-cp rat (cp/cp) is a useful model for study of the metabolic consequences of obesity and hyperinsulinemia. To assess the effect of hyperinsulinemia on VLDL secretion in this model, we measured rates of secretion of VLDL in perfused livers derived from cp/cp rats and their lean littermates. Livers of cp/cp rats secreted significantly greater amounts of VLDL triglyceride and apolipoprotein, compared with lean littermates. The content of apoB, apoE, and apoCs in both perfusate and plasma VLDL was greater in the cp/cp rat, as was the apolipoprotein (apo)C, apoA-I, and apoA-IV content of plasma HDL. Triglyceride content was also greater in cp/cp livers, as was hepatic lipogenesis and expression of lipogenic enzymes and sterol regulatory element binding protein-1 (SREBP-1). Hepatic mRNAs for apoE, and apoA-I were higher in livers of cp/cp rats. In contrast, the steady state levels of apoC-II, apoC-III, and apoB mRNAs were unchanged. Thus, livers of obese hyperinsulinemic cp/cp JCR:LA-cp rats secrete a greater number of VLDL particles that are enriched in triglyceride, apoE, and apoC. Greater secretion of VLDL in the cp/cp rat in part results from higher endogenous fatty acid synthesis, which in turn may occur in response to increased expression of the lipogenic enzyme regulator SREBP-1c.

  8. VLDL hydrolysis by LPL activates PPAR-alpha through generation of unbound fatty acids.

    Science.gov (United States)

    Ruby, Maxwell A; Goldenson, Benjamin; Orasanu, Gabriela; Johnston, Thomas P; Plutzky, Jorge; Krauss, Ronald M

    2010-08-01

    Recent evidence suggests that lipoproteins serve as circulating reservoirs of peroxisomal proliferator activated receptor (PPAR) ligands that are accessible through lipolysis. The present study was conducted to determine the biochemical basis of PPAR-alpha activation by lipolysis products and their contribution to PPAR-alpha function in vivo. PPAR-alpha activation was measured in bovine aortic endothelial cells following treatment with human plasma, VLDL lipolysis products, or oleic acid. While plasma failed to activate PPAR-alpha, oleic acid performed similarly to VLDL lipolysis products. Therefore, fatty acids are likely to be the PPAR-alpha ligands generated by VLDL lipolysis. Indeed, unbound fatty acid concentration determined PPAR-alpha activation regardless of fatty acid source, with PPAR-alpha activation occurring only at unbound fatty acid concentrations that are unachievable under physiological conditions without lipase action. In mice, a synthetic lipase inhibitor (poloxamer-407) attenuated fasting-induced changes in expression of PPAR-alpha target genes. Apolipoprotein CIII (apoCIII), an endogenous inhibitor of lipoprotein and hepatic lipase, regulated access to the lipoprotein pool of PPAR-alpha ligands, because addition of exogenous apoCIII inhibited, and removal of endogenous apoCIII potentiated, lipolytic PPAR-alpha activation. These data suggest that the PPAR-alpha response is generated by unbound fatty acids released locally by lipase activity and not by circulating plasma fatty acids.

  9. Concentrating small particles in protoplanetary disks through the streaming instability

    CERN Document Server

    Yang, Chao-Chin; Carrera, Daniel

    2016-01-01

    Laboratory experiments indicate that direct growth of silicate grains via mutual collisions can only produce particles up to roughly millimeters in size. On the other hand, recent simulations of the streaming instability have shown that mm/cm-sized particles require an excessively high metallicity for dense filaments to emerge. Using the numerical algorithm of Yang & Johansen (2016) for stiff mutual drag force, we revisit the investigations of Carrera et al. (2015) and perform simulations of small particles with significantly higher resolutions and longer simulation times. We find that particles of dimensionless stopping time $\\tau_\\mathrm{s} = 10^{-2}$ and $10^{-3}$ -- representing mm- and cm-sized particles interior of the water ice line -- concentrate themselves via the streaming instability at a solid abundance of a few percent. We thus revise the critical solid abundance curve of Carrera et al. (2015) for the regime of $\\tau_\\mathrm{s} \\ll 1$. The solid density in the concentrated regions reaches val...

  10. Genesis Concentrator Target Particle Contamination Mapping and Material Identification

    Science.gov (United States)

    Calaway, Michael J.; Rodriquez, M. C.; Allton, J. H.

    2007-01-01

    The majority of surface particles were found to be Genesis science team as well as ultra-pure water megasonic cleaning by the JSC team [4]. Removal of organic contamination from target materials is also being investigated by the science team with the use of UV-ozone cleaning devices at JSC and Open University [5]. In preparation for solar wind oxygen analyses at UCLA and Open University [1, 2], surface particle contamination on three Genesis concentrator targets was closely examined to evaluate cleaning strategies. Two silicon carbide (Genesis sample # 60001 and 60003) and one chemical vapor deposited (CVD) 13C concentrator target (60002) were imaged and mosaic mapped with optical microscopes. The resulting full target mosaic images and particle feature maps were subsequently compared with non-flight, but flight-like, concentrator targets and sample return capsule (SRC) materials. Contamination found on the flown concentrator acceleration grid was further examined using a scanning electron microscope (SEM). Energy dispersive X-ray spectroscopy (EDS) for particle identification was subsequently compared with the optical images from the flown targets. Figure 1 show that all three targets imaged in this report are fully intact and do not show any signs of material fractures. However, previous ellipsometry results and overview imaging of both flown SiC targets show a solar wind irradiation gradient from the center focal point to the outer edge [3]. In addition, due to the hard landing, each target has experienced varying degrees of impacts, scratches, and particle debris from the spacecraft and Utah impact site.

  11. GLP-1 receptor activation inhibits VLDL production and reverses hepatic steatosis by decreasing hepatic lipogenesis in high-fat-fed APOE*3-Leiden mice.

    Directory of Open Access Journals (Sweden)

    Edwin T Parlevliet

    Full Text Available OBJECTIVE: In addition to improve glucose intolerance, recent studies suggest that glucagon-like peptide-1 (GLP-1 receptor agonism also decreases triglyceride (TG levels. The aim of this study was to evaluate the effect of GLP-1 receptor agonism on very-low-density lipoprotein (VLDL-TG production and liver TG metabolism. EXPERIMENTAL APPROACH: The GLP-1 peptide analogues CNTO3649 and exendin-4 were continuously administered subcutaneously to high fat diet-fed APOE*3-Leiden transgenic mice. After 4 weeks, hepatic VLDL production, lipid content, and expression profiles of selected genes involved in lipid metabolism were determined. RESULTS: CNTO3649 and exendin-4 reduced fasting plasma glucose (up to -30% and -28% respectively and insulin (-43% and -65% respectively. In addition, these agents reduced VLDL-TG production (-36% and -54% respectively and VLDL-apoB production (-36% and -43% respectively, indicating reduced production of VLDL particles rather than reduced lipidation of apoB. Moreover, they markedly decreased hepatic content of TG (-39% and -55% respectively, cholesterol (-30% and -55% respectively, and phospholipids (-23% and -36% respectively, accompanied by down-regulation of expression of genes involved in hepatic lipogenesis (Srebp-1c, Fasn, Dgat1 and apoB synthesis (Apob. CONCLUSION: GLP-1 receptor agonism reduces VLDL production and hepatic steatosis in addition to an improvement of glycemic control. These data suggest that GLP-receptor agonists could reduce hepatic steatosis and ameliorate dyslipidemia in patients with type 2 diabetes mellitus.

  12. Boron concentration measurement in biological tissues by charged particle spectrometry.

    Science.gov (United States)

    Bortolussi, S; Altieri, S

    2013-11-01

    Measurement of boron concentration in biological tissues is a fundamental aspect of boron neutron capture therapy, because the outcome of the therapy depends on the distribution of boron at a cellular level, besides on its overall concentration. This work describes a measurement technique based on the spectroscopy of the charged particles emitted in the reaction (10)B(n,α)(7)Li induced by thermal neutrons, allowing for a quantitative determination of the boron concentration in the different components that may be simultaneously present in a tissue sample, such as healthy cells, tumor cells and necrotic cells. Thin sections of tissue containing (10)B are cut at low temperatures and irradiated under vacuum in a thermal neutron field. The charged particles arising from the sample during the irradiation are collected by a thin silicon detector, and their spectrum is used to determine boron concentration through relatively easy calculations. The advantages and disadvantages of this technique are here described, and validation of the method using tissue standards with known boron concentrations is presented.

  13. Characterization of ultrafine particle number concentration and new particle formation in urban environment of Taipei, Taiwan

    Science.gov (United States)

    Cheung, H. C.; Chou, C. C.-K.; Huang, W.-R.; Tsai, C.-Y.

    2013-04-01

    An intensive aerosol characterization experiment was performed at the Taipei Aerosol and Radiation Observatory (TARO, 25.02° N, 121.53° E) in the urban area of Taipei, Taiwan during July 2012. Number concentration and size distribution of aerosol particles were measured continuously, which were accompanied by concurrent measurements of mass concentration of submicron particles, PM (d ≤ 1 μm), and photolysis rate of ozone, J(O1D). The averaged number concentrations of total (Ntotal), accumulation mode (Nacu), Aitken mode (Ntotal), and nucleation mode (Nnuc) particles were 7.6 × 103 cm-3, 1.2 × 103 cm-3, 4.4 × 103 cm-3, and 1.9 × 103 cm-3, respectively. Accordingly, the ultrafine particles (UFPs, d ≤ 100 nm) accounted for 83% of the total number concentration of particles measured in this study (10 ≤ d ≤ 429 nm), indicating the importance of UFPs to the air quality and radiation budget in Taipei and its surrounding areas. An averaged Nnuc/NOx ratio of ~60 cm-3 ppbv-1 was derived from nighttime measurements, which was suggested to be the characteristic of vehicle emissions that contributed to the "urban background" of nucleation mode particles throughout a day. On the contrary, it was found that the number concentration of nucleation mode particles was independent of NOx and could be elevated up to 10 times the "urban background" levels during daytime, suggesting a substantial amount of nucleation mode particles produced from photochemical processes. Consistency in the time series of the nucleation mode particle concentration and the proxy of H2SO4 production, UVB·SO2, for new particle formation (NPF) events showed that photo-oxidation of SO2 was responsible for the formation of new particles in our study area. Moreover, analysis upon the diameter growth rate, GR, and formation rate of nucleation mode particles, J10-25, found that the values of GR (8.5 ± 6.8 nm h-1) in Taipei were comparable to other urban areas, whereas the values of J10-25 (2.2 ± 1

  14. Outdoor ultrafine particle concentrations in front of fast food restaurants.

    Science.gov (United States)

    Vert, Cristina; Meliefste, Kees; Hoek, Gerard

    2016-01-01

    Ultrafine particles (UFPs) have been associated with negative effects on human health. Emissions from motor vehicles are the principal source of UFPs in urban air. A study in Vancouver suggested that UFP concentrations were related to density of fast food restaurants near the monitoring sites. A previous monitoring campaign could not separate the contribution of restaurants from road traffic. The main goal of this study has been the quantification of fast food restaurants' contribution to outdoor UFP concentrations. A portable particle number counter (DiscMini) has been used to carry out mobile monitoring in a largely pedestrianized area in the city center of Utrecht. A fixed route passing 17 fast food restaurants was followed on 8 days. UFP concentrations in front of the restaurants were 1.61 times higher than in a nearby square without any local sources used as control area and 1.22 times higher compared with all measurements conducted in between the restaurants. Adjustment for other sources such as passing mopeds, smokers or candles did not explain the increase. In conclusion, fast food restaurants result in significant increases in outdoor UFP concentrations in front of the restaurant.

  15. Particle number concentrations near the Rome-Ciampino city airport

    Science.gov (United States)

    Stafoggia, M.; Cattani, G.; Forastiere, F.; Di Menno di Bucchianico, A.; Gaeta, A.; Ancona, C.

    2016-12-01

    Human exposure to ultrafine particles (UFP) has been postulated to be associated with adverse health effects, and there is interest regarding possible measures to reduce primary emissions. One important source of UFP are airport activities, with aircraft take-offs being the most relevant one. We implemented two measurement campaigns of total particle number concentrations (PNC), a proxy for UFP, near a medium-size airport in central Italy. One-minute PNC averages were collected on June 2011 and January 2012 concurrently with 30-min average meteorological data on temperature and wind speed/direction. Data on minute-specific take-offs and landings were obtained by the airport authorities. We applied statistical regression models to relate PNC data to the presence of aircraft activities while adjusting for time trends and meteorology, and estimated the increases in PNC ±15 min before and after take-offs and landings. We repeated the analyses considering prevalent wind direction and by size of the aircraft. We estimated PNC increases of 5400 particles/cm3/minute during the 15 min before and after take-offs, with a peak of 19,000 particles/cm3/minute within 5 min after take-offs. Corresponding figures for landings were 1300 and 1000 particles, respectively. The highest PNC estimates were obtained when the prevailing wind came from the runway direction, and led to estimated PNC increases of 60,000 particles/cm3/minute within 5 min after take-offs. No main differences were noted from the exhaust of different types of aircrafts. The area surrounding Ciampino airport is densely inhabited, raising concerns about the potential adverse effects of long-term and short-term exposure to airport-borne UFP. A close monitoring of airport activities and emissions is mandatory to reduce the public health impact of the airport on the nearby population.

  16. Decreasing particle number concentrations in a warming atmosphere and implications

    Directory of Open Access Journals (Sweden)

    F. Yu

    2012-03-01

    Full Text Available New particle formation contributes significantly to the number concentration of condensation nuclei (CN as well as cloud CN (CCN, a key factor determining aerosol indirect radiative forcing of the climate system. Using a physics-based nucleation mechanism that is consistent with a range of field observations of aerosol formation, it is shown that projected increases in global temperatures could significantly inhibit new particle, and CCN, formation rates worldwide. An analysis of CN concentrations observed at four NOAA ESRL/GMD baseline stations since the 1970s and two other sites since 1990s reveals long-term decreasing trends that are consistent in sign with, but are larger in magnitude than, the predicted temperature effects. The possible reasons for larger observed long-term CN reductions at remote sites are discussed. The combined effects of rising temperatures on aerosol nucleation rates and other chemical and microphysical processes may imply substantial decreases in future tropospheric particle abundances associated with global warming, delineating a potentially significant feedback mechanism that increases Earth's climate sensitivity to greenhouse gas emissions. Further research is needed to quantify the magnitude of such a feedback process.

  17. The effect of interaction between Lipoprotein Lipase and ApoVLDL-II ...

    African Journals Online (AJOL)

    The effect of interaction between Lipoprotein Lipase and ApoVLDL-II genes on fat and serum biochemical levels. ... Single nucleotide polymorphism (SNP) in apoVLDL-II and lipoprotein lipase genes was screened by ... Article Metrics.

  18. A new combined multicompartmental model for apolipoprotein B-100 and triglyceride metabolism in VLDL subfractions

    National Research Council Canada - National Science Library

    Adiels, Martin; Packard, Chris; Caslake, Muriel J; Stewart, Philip; Soro, Aino; Westerbacka, Jukka; Wennberg, Bernt; Olofsson, Sven-Olof; Taskinen, Marja-Riitta; Borén, Jan

    ...)-containing lipoproteins in humans. The aim of this study was to develop a multicompartment model that allows us to simultaneously determine the kinetics of apoB and triglyceride (TG) in VLDL(1) and VLDL(2...

  19. Positional distribution of decanoic acid: Effect on chylomicron and VLDL TAG structures and postprandial lipemia

    DEFF Research Database (Denmark)

    Yli-Jokipii, K.M.; Schwab, U.S.; Tarvonen, R.L.;

    2004-01-01

    Although medium-chain FA (MCFA) are mainly absorbed via the portal venous system, they are also incorporated into chylomicron TAG; therefore, the positional distribution of MCFA in TAG is likely to affect their metabolic fate. We studied chylomicron and VLDL TAG structures, as well as the magnitu...... or in FFA concentrations. Thus, the positional distribution of MCFA in TAG affects their metabolic fate, but the magnitude of postprandial lipemia does not seem to be dependent on the positional distribution of MCFA in the ingested fat....

  20. Sedimentation of concentrated monodisperse colloidal suspensions: role of collective particle interaction forces.

    Science.gov (United States)

    Vesaratchanon, Jan S; Nikolov, Alex; Wasan, Darsh T

    2008-06-01

    The sedimentation velocities and concentration profiles of low-charge, monodisperse hydroxylate latex particle suspensions were investigated experimentally as a function of the particle concentration to study the effects of the collective particle interactions on suspension stability. We used the Kossel diffraction technique to measure the particle concentration profile and sedimentation rate. We conducted the sedimentation experiments using three different particle sizes. Collective hydrodynamic interactions dominate the particle-particle interactions at particle concentrations up to 6.5 vol%. However, at higher particle concentrations, additional collective particle-particle interactions resulting from the self-depletion attraction cause particle aggregation inside the suspension. The collective particle-particle interaction forces play a much more important role when relatively small particles (500 nm in diameter or less) are used. We developed a theoretical model based on the statistical particle dynamics simulation method to examine the role of the collective particle interactions in concentrated suspensions in the colloidal microstructure formation and sedimentation rates. The theoretical results agree with the experimentally-measured values of the settling velocities and concentration profiles.

  1. FINE AND COARSE PARTICLES: CONCENTRATION RELATIONSHIPS RELEVANT TO EPIDEMIOLOGICAL STUDIES

    Science.gov (United States)

    Fine particles and coarse particles are defined in terms of the modal structure of particle size distributions typically observed in the atmosphere. Differences among the various modes are discussed. The fractions of fine and coarse particles collected in specific size ranges, ...

  2. Impaired Insulin Suppression of VLDL-Triglyceride Kinetics in Non-alcoholic Fatty Liver Disease

    DEFF Research Database (Denmark)

    Poulsen, Marianne K; Nellemann, Birgitte; Stødkilde-Jørgensen, Hans;

    2016-01-01

    CONTEXT: Non-alcoholic fatty liver disease (NAFLD) is associated with glucose and lipid metabolic abnormalities. However, insulin suppression of VLDL-triglyceride (VLDL-TG) kinetics is not fully understood. OBJECTIVE: To determine VLDL-TG, glucose and palmitate kinetics during fasting and hyperin......CONTEXT: Non-alcoholic fatty liver disease (NAFLD) is associated with glucose and lipid metabolic abnormalities. However, insulin suppression of VLDL-triglyceride (VLDL-TG) kinetics is not fully understood. OBJECTIVE: To determine VLDL-TG, glucose and palmitate kinetics during fasting...... and hyperinsulinemia in men with (NAFLD+) and without NAFLD (NAFLD-). DESIGN: 27 non-diabetic, upper-body obese (WHR >0.9, BMI >28 kg/m(2)) men, 18 NAFLD+ and 9 NAFLD- determined by magnetic resonance spectroscopy, were enrolled.(14)C-labeled VLDL-TG and (3)H-labeled glucose and palmitate tracers were applied...... metabolic abnormalities associated with NAFLD and presumably diabetes....

  3. Lipoprotein particles and incident type 2 diabetes in the multi-ethnic study of atherosclerosis.

    Science.gov (United States)

    Mackey, Rachel H; Mora, Samia; Bertoni, Alain G; Wassel, Christina L; Carnethon, Mercedes R; Sibley, Christopher T; Goff, David C

    2015-04-01

    In the Multi-Ethnic Study of Atherosclerosis (MESA), we evaluated associations of baseline levels of a lipoprotein-based insulin resistance (IR) index (LP-IR), IR-related lipoprotein particles, mean particle sizes, and lipids, with incident type 2 diabetes, independent of confounders, glucose, insulin, and HOMA-IR. Among 5,314 adults aged 45-84 years without baseline diabetes or cardiovascular disease, 656 cases of diabetes were identified during a mean follow-up of 7.7 years. Lipoprotein particle concentrations, size, and LP-IR were determined by nuclear magnetic resonance spectroscopy of stored baseline plasma. Potential effect modification, by race/ethnicity, sex, baseline use of lipid-lowering medications or hormone therapy, or glucose strata (diabetes adjusted for confounders and glucose or insulin. These also were similar by race/ethnicity, sex, and treatment group. Associations were similar for LP-IR, large VLDL-P, mean VLDL size, TG, and TG-to-HDL-C ratio; they persisted for LP-IR, large VLDL-P, or mean VLDL size adjusted for HOMA-IR or TG-to-HDL-C ratio and glucose but not for the TG-to-HDL-C ratio adjusted for LP-IR or for HOMA-IR or insulin if adjusted for LP-IR and glucose. Among ethnically diverse men and women, LP-IR, large VLDL-P, large VLDL size, TG, and TG-to-HDL-C ratio were associated with incident diabetes independent of established risk factors, glucose, insulin, or HOMA-IR, as well as the use of lipid-lowering medications or hormone therapy. © 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  4. Method and apparatus for measuring particle size at low concentration

    NARCIS (Netherlands)

    Marijnissen, J.C.M.; Willemse, A.W.; Roos, R.A.

    1997-01-01

    Described is an improved method for measuring the particle size of ultrasmall particles (111) which are suspended in a fluid. Laser light (121) is scattered by the particles, and the scattered light (122) is received by a light detector (131) which provides an electrical measuring signal (Sm) which

  5. Effect of Alternative Splicing of VLDL Receptor on its Ligand Binding and Internalization Capability

    Institute of Scientific and Technical Information of China (English)

    Ying-Hong LI; Jun TIAN; Tao CHEN; Yi-Qiang ZONG; Yu WANG; Pu YANG; Shen QU

    2005-01-01

    @@ 1 Introduction Very low density lipoprotein receptor (VLDL-R) is a main receptor mediating the uptake of triglyceride-rich lipoprotein(TRL), so it is in all probability to play an important role in the development of atherosclerosis(AS). On account of alternative splicing of O-linked carbohydrate chains in extracellular fragment, VLDL-R can be classified into two isoforms: VLDL-R Ⅰ with O-linker sugar region, while VLDL-R Ⅱ without this domain[1].But so far, the difference of their function and biological significance between two isoforms, especially those of VLDL-R Ⅱ has not been clarified. In our research, ldlA7 cell strains stably expressing two isoforms of VLDL-R were obtained through gene clone technology. Binding and internalization of the natural ligands (VLDL and β-VLDL)of two types VLDL-R and their roles in the formation of foam cells were compared to clarify the difference between two isoforms of VLDL-R, and elucidate their roles in the metabolism of lipoprotein and development of AS.

  6. Method and apparatus for measuring particle size at low concentration

    OpenAIRE

    Marijnissen, J.C.M.; Willemse, A.W.; Roos, R A

    1997-01-01

    Described is an improved method for measuring the particle size of ultrasmall particles (111) which are suspended in a fluid. Laser light (121) is scattered by the particles, and the scattered light (122) is received by a light detector (131) which provides an electrical measuring signal (Sm) which is representative of the intensity of the scattered light (122). According to the present invention, signal components with a relatively low characteristic frequency are removed from the electrical...

  7. Expression of the very low-density lipoprotein receptor (VLDL-r), an apolipoprotein-E receptor, in the central nervous system and in Alzheimer`s disease

    Energy Technology Data Exchange (ETDEWEB)

    Christie, R.H.; Chung, Haeyong; Rebeck, G.W.; Hyman, B.T. [Massachusetts General Hospital, Boston, MA (United States)] [and others

    1996-04-01

    The very low density lipoprotein receptor (VLDL-r) is a cell-surface molecule specialized for the internalization of multiple diverse ligands, including apolipoprotein E (apoE)-containing lipoprotein particles, via clathrin-coated pits. Its structure is similar to the low-density lipoprotein receptor (LDL-r), although the two have substantially different systemic distributions and regulatory pathways. The present work examines the distribution of VLDL-r in the central nervous system (CNS) and in relation to senile plaques in Alzheimer disease (AD). VLDL-r is present on resting and activated microglia, particularly those associated with senile plaques (SPs). VLDL-r immunoreactivity is also found in cortical neurons. Two exons of VLDL-r mRNA are differentially spliced in the mature receptor mRNA. One set of splice forms gives rise to receptors containing (or lacking) an extracellular O-linked glycosylation domain near the transmembrane portion of the molecule. The other set of splice forms appears to be brain-specific, and is responsible for the presence or absence of one of the cysteine-rich repeat regions in the binding region of the molecule. Ratios of the receptor variants generated from these splice forms do not differ substantially across different cortical areas or in AD. We hypothesize that VLDL-r might contribute to metabolism of apoE and apoE/A{beta} complexes in the brain. Further characterization of apoE receptors in Alzheimer brain may help lay the groundwork for understanding the role of apoE in the CNS and in the pathophysiology of AD. 43 refs., 5 figs.

  8. Isolated hyperglycaemia does not increase VLDL-triacylglycerol secretion in type 1 diabetic men

    DEFF Research Database (Denmark)

    Johansen, Rakel Fuglsang; Søndergaard, Esben; Sørensen, Lars Peter

    2015-01-01

    AIMS/HYPOTHESIS: In type 1 diabetes, abnormalities of both glucose and lipoprotein metabolism are seen. The relationship between these factors is not understood, but studies indicate that hyperglycaemia may increase hepatic VLDL-triacylglycerol (VLDL-TG) secretion and reduce VLDL-TG fatty acid...... oxidation, which could lead to the development of dyslipidaemia. The aim of this study was to determine the isolated effect of hyperglycaemia on VLDL-TG and NEFA kinetics in men with type 1 diabetes. METHODS: VLDL-TG and palmitate kinetics were measured in eight men with type 1 diabetes using ex vivo...... of acute hyperglycaemia (16 mmol/l) without a concomitant increase in insulin does not alter VLDL-TG and NEFA kinetics in men with type 1 diabetes. Clinical trial registry number: NCT01178957....

  9. [The impact of a 14- day regular physical exercise regime on the concentration of the classes and subclasses of lipoprotein particles in young subjects with a sedentary lifestyle].

    Science.gov (United States)

    Sabaka, P; Dukát, A; Oravec, S; Mistríková, L; Baláž, D; Bendžala, M; Gašpar, L

    2013-10-01

    Recommendations from the cardiological professional companies working in the area of primary prevention of cardiovascular diseases put an emphasis on regular aerobic physical activity. Its positive effect on both cardiovascular and overall mortality has repea-tedly been proven by the observations of prospective and cross sectional epidemiological studies. One of the possible explanations of this positive effect is a change in the concentration of lipoprotein classes and their subclasses, which is expressed as a change in their average size. In a group of young healthy men and women with a sedentary lifestyle we observed the effect of medium intensive physical exercise in the form of a 30- minute slow run per day lasting for 14 days. The concentration of lipoprotein classes and subclasses were determined through the method of a linear electrophoresis in polyacrylamide gel. In the observed group we found a statistically significant decrease of VLDL, large IDL particles, medium sized LDL, small dense LDL, and medium sized HDL particles. In the light of current knowledge all these lipoprotein particles are deemed as atherogenic. Thus, as little as 14 days of regular exercising has a positive effect on the concentration of plasmatic lipoproteins, and emphasises the role of regular physical activity in the primary prevention of cardiovascular diseases.

  10. Effect of Alternative Splicing of VLDL Receptor on its Ligand Binding and Internalization Capability

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    1 IntroductionVery low density lipoprotein receptor (VLDL-R) is a main receptor mediating the uptake of triglyceride-rich lipoprotein(TRL), so it is in all probability to play an important role in the development of atherosclerosis (AS). On account of alternative splicing of O-linked carbohydrate chains in extracellular fragment, VLDL-R can be classified into two isoforms: VLDL-RⅠ with O-linker sugar region, while VLDL-RⅡ without this domain~([1]). But so far, the difference of their function and biological...

  11. Temporal change in the {sup 137}Cs concentration ratio between coarse and fine particles in Fukushima

    Energy Technology Data Exchange (ETDEWEB)

    Kitayama, K.; Ohse, K.; Kawatsu, K.; Tsukada, H. [Fukushima University, 1 Kanayagawa, Fukushima-shi, Fukushima 960-1260 (Japan)

    2014-07-01

    Many radionuclides were released into the atmosphere by the Fukushima Daiichi Nuclear Power Plant accident, which was caused by the tsunami following the Tohoku Region Pacific Coast Earthquake on March 11, 2011. A major radionuclide released into the environment was radiocesium. Radiocesium has a long lifetime, which allows it to remain in the environment for a prolonged period. Most radiocesium exists in soil particles, and a potential source of radiocesium in coarse particles was resuspended from soil particles. Therefore, the {sup 137}Cs concentration ratios between coarse and fine particles were important for the evaluation of the radiocesium source. In this study, the {sup 137}Cs atmospheric concentrations in coarse and fine particles were measured in Fukushima. Airborne particles were collected from September 2012 to July 2013 at two sites, Fukushima and Date, which are 62 and 55 km, respectively, from the Fukushima Daiichi Nuclear Power Plant. The coarse and fine particles were categorized by a 50% cutoff diameter of 1.1 μm. The sampling filters were exchanged once every half month. The radioactivity of {sup 137}Cs in the samples was measured for 10800-86400 s by the Ge detector. In Fukushima, the total {sup 137}Cs concentration in coarse and fine particles ranged from 20 to 370 μBq m{sup -3}: 7-270 μBq m{sup -3} for coarse particles and 10-170 μBq m{sup -3} for fine particles. In Date, the total concentration ranged from 100 to 310 μBq m{sup -3}: 60-220 μBq m{sup -3} for coarse particles and 10-170 μBq m{sup -3} for fine particles. The {sup 137}Cs concentrations at the two sites were found to be comparable. The average concentration at the two sites for the course and fine particles were 110 and 55 μBq m{sup -3}, respectively, and the total concentration was 166 μBq m{sup -3}. The {sup 137}Cs concentration in coarse particles accounted for 30%-90% of the total concentration, with an average of 67%. On comparing with the ratio before the study, the

  12. Atorvastatin and Fenofibrate have Comparable Effects on VLDL-Apolipoprotein C-III Kinetics in Men with the Metabolic Syndrome

    Science.gov (United States)

    Chan, Dick C; Watts, Gerald F; Ooi, Esther M.M; Ji, Juying; Johnson, Anthony G; Barrett, P Hugh R

    2009-01-01

    Objectives The metabolic syndrome (MetS) is characterised by insulin resistance and dyslipidemia that may accelerate atherosclerosis. Disturbed apolipoprotein (apo) C-III metabolism may account for dyslipidemia in these subjects. Atorvastatin and fenofibrate decrease plasma apoC-III, but the underlying mechanisms are not fully understood. Methods and Results The effects of atorvastatin (40 mg/d) and fenofibrate (200mg/d) on the kinetics of very-low density lipoprotein (VLDL)-apoC-III were investigated in a cross-over trial of 11 MetS men. VLDL-apoC-III kinetics were studied, following intravenous d3-leucine administration using gas chromatography-mass spectrometry and compartmental modeling. Compared with placebo, both atorvastatin and fenofibrate significantly decreased (Ptriglyceride, apoB, apoB-48 and total apoC-III. Atorvastatin, not fenofibrate, significantly decreased plasma apoA-V concentrations (Pkinetics in MetS; reduced production and increased fractional catabolism of VLDL-apoC-III may explain the triglyceride-lowering effect of these agents. PMID:18566295

  13. Micro-scale variability of urban particle number and mass concentrations in Leipzig, Germany

    Energy Technology Data Exchange (ETDEWEB)

    Birmili, Wolfram; Rehn, Johanna; Rasch, Fabian [Leibniz Institute for Tropospheric Research (Tropos), Leipzig (Germany); Vogel, Andreas; Boehlke, Christoph; Weber, Konradin [Fachhochschule Duesseldorf (Germany). FB4 - Umweltmesstechnik

    2013-04-15

    We investigated the micro-scale variability of particle number and mass concentrations in the urban atmosphere of Leipzig, Germany. Particles were sampled in May and June 2011 using portable instrumentation along a fixed measurement route, representing different degrees of outdoor particle exposure that can be experienced by a pedestrian. The instrumentation comprised a Grimm NanoCheck sensor for particle number (25-300 nm) and a Grimm OPC for particle mass concentrations. The mobile measurements conducted at a time resolution of 10 s revealed rich details in the spatio-temporal distribution of urban particles that were not visible in fixed-site measurements. Motor traffic proved to be a major source of particle number and mass in the area, although the corresponding concentrations declined rapidly when moving away from the traffic sources. The experiments demonstrate that traffic-free zones and green park areas are useful measures to limit outdoor exposure to traffic-related particles even if they are rather modest in size. Unexpected findings include high fine particle concentrations (PM{sub [0.25;1]}) near outdoor seating areas of restaurants, and the apparent dependence of coarse particle concentrations (PM{sub [2.5;10]}) on the ability of surfaces to release particles by resuspension. The study illustrates the usefulness of the spatial sensing of airborne particles in the urban roughness layer and encourages the use of such data for the validation of micro-scale dispersion models. (orig.)

  14. Factors affecting the concentration of outdoor particles indoors (COPI): Identification of data needs and existing data

    Energy Technology Data Exchange (ETDEWEB)

    Thatcher, Tracy L.; McKone, Thomas E.; Fisk, William J.; Sohn, Michael D.; Delp, Woody W.; Riley, William J.; Sextro, Richard G.

    2001-12-01

    The process of characterizing human exposure to particulate matter requires information on both particle concentrations in microenvironments and the time-specific activity budgets of individuals among these microenvironments. Because the average amount of time spent indoors by individuals in the US is estimated to be greater than 75%, accurate characterization of particle concentrations indoors is critical to exposure assessments for the US population. In addition, it is estimated that indoor particle concentrations depend strongly on outdoor concentrations. The spatial and temporal variations of indoor particle concentrations as well as the factors that affect these variations are important to health scientists. For them, knowledge of the factors that control the relationship of indoor particle concentrations to outdoor levels is particularly important. In this report, we identify and evaluate sources of data for those factors that affect the transport to and concentration of outdoor particles in the indoor environment. Concentrations of particles indoors depend upon the fraction of outdoor particles that penetrate through the building shell or are transported via the air handling (HVAC) system, the generation of particles by indoor sources, and the loss mechanisms that occur indoors, such as deposition. To address these issues, we (i) identify and assemble relevant information including the behavior of particles during air leakage, HVAC operations, and particle filtration; (ii) review and evaluate the assembled information to distinguish data that are directly relevant to specific estimates of particle transport from those that are only indirectly useful and (iii) provide a synthesis of the currently available information on building air-leakage parameters and their effect on indoor particle matter concentrations.

  15. Characterization of in Vitro Modified Human Very Low-Density Lipoprotein Particles and Phospholipids by Capillary Electrophoresis

    Directory of Open Access Journals (Sweden)

    Chin-Pong Chong

    2012-12-01

    Full Text Available A simple capillary zone electrophoresis (CZE method was used to characterize human very low-density lipoprotein (VLDL particles for four healthy donors. One major peak was observed for native, in vitro oxidized and glycated VLDL particles. The effective mobilities and peak areas of the capillary electrophoresis (CE profiles showed good reproducibility and precision. The mobility of the oxidized VLDL peak was higher than that of the native VLDL. The mobility of the glycated VLDL peak was similar to that of the native VLDL. Phospholipids isolated from VLDL particles were analyzed by our recently developed micellar electrokinetic chromatography (MEKC with a high-salt stacking method. At absorbance 200 nm, the native VLDL phospholipids showed a major peak and a minor peak for each donor. For oxidized VLDL phospholipids, the area of the major peak reduced for three donors, possibly due to phospholipid decomposition. For glycated VLDL phospholipids, the peak mobilities were more positive than native VLDL phospholipids for two donors, possibly due to phospholipid-linked advanced glycation end products (AGEs. Very interestingly, at absorbance 234 nm, the major peak of oxidized VLDL phospholipids was resolved as two peaks for each donor, possibly due to conjugated dienes formed upon oxidation.

  16. Characterization of in vitro modified human very low-density lipoprotein particles and phospholipids by capillary electrophoresis.

    Science.gov (United States)

    Liu, Yi-Ning; Shu, Ting-Yu; Xie, Huai-Guang; Lai, Wei-Ting; Liao, Yi-Han; Su, Mei-Yu; Lin, You-Sian; Chen, Yen-Yi; Lin, Yi-Jyun; Chong, Chin-Pong; Liu, Mine-Yine

    2012-12-03

    A simple capillary zone electrophoresis (CZE) method was used to characterize human very low-density lipoprotein (VLDL) particles for four healthy donors. One major peak was observed for native, in vitro oxidized and glycated VLDL particles. The effective mobilities and peak areas of the capillary electrophoresis (CE) profiles showed good reproducibility and precision. The mobility of the oxidized VLDL peak was higher than that of the native VLDL. The mobility of the glycated VLDL peak was similar to that of the native VLDL. Phospholipids isolated from VLDL particles were analyzed by our recently developed micellar electrokinetic chromatography (MEKC) with a high-salt stacking method. At absorbance 200 nm, the native VLDL phospholipids showed a major peak and a minor peak for each donor. For oxidized VLDL phospholipids, the area of the major peak reduced for three donors, possibly due to phospholipid decomposition. For glycated VLDL phospholipids, the peak mobilities were more positive than native VLDL phospholipids for two donors, possibly due to phospholipid-linked advanced glycation end products (AGEs). Very interestingly, at absorbance 234 nm, the major peak of oxidized VLDL phospholipids was resolved as two peaks for each donor, possibly due to conjugated dienes formed upon oxidation.

  17. Characterization of ultrafine particle number concentration and new particle formation in an urban environment of Taipei, Taiwan

    Science.gov (United States)

    Cheung, H. C.; Chou, C. C.-K.; Huang, W.-R.; Tsai, C.-Y.

    2013-09-01

    An intensive aerosol characterization experiment was performed at the Taipei Aerosol and Radiation Observatory (TARO, 25.02° N, 121.53° E) in the urban area of Taipei, Taiwan, during July 2012. Number concentration and size distribution of aerosol particles were measured continuously, which were accompanied by concurrent measurements of mass concentration of submicron particles, PM1 (d ≤ 1 μm), and photolysis rate of ozone, J(O1D). The averaged number concentrations of total (Ntotal), accumulation mode (Nacu), Aitken mode (NAitken), and nucleation mode (Nnuc) particles were 13.9 × 103 cm-3, 1.2 × 103 cm-3, 6.1 × 103 cm-3, and 6.6 × 103 cm-3, respectively. Accordingly, the ultrafine particles (UFPs, d ≤ 100 nm) accounted for 91% of the total number concentration of particles measured in this study (10 ≤ d ≤ 429 nm), indicating the importance of UFPs to the air quality and radiation budget in Taipei and its surrounding areas. An averaged Nnuc / NOx ratio of 192.4 cm-3 ppbv-1 was derived from nighttime measurements, which was suggested to be the characteristic of vehicle emissions that contributed to the "urban background" of nucleation mode particles throughout a day. On the contrary, it was found that the number concentration of nucleation mode particles was independent of NOx and could be elevated up to 10 times of the "urban background" levels during daytime, suggesting a substantial amount of nucleation mode particles produced from photochemical processes. Averages (± 1σ) of the diameter growth rate (GR) and formation rate of nucleation mode particles, J10, were 11.9 ± 10.6 nm h-1 and 6.9 ± 3.0 cm-3 s-1, respectively. Consistency in the time series of the nucleation mode particle concentration and the proxy of H2SO4 production, UVB · SO2/CS, for new particle formation (NPF) events suggested that photooxidation of SO2 was likely one of the major mechanisms for the formation of new particles in our study area. Moreover, it was revealed that the

  18. Whey protein particles modulate mechanical properties of gels at high protein concentrations

    NARCIS (Netherlands)

    Saglam, D.; Venema, P.; Vries, de R.J.; Berg, van den L.; Linden, van der E.

    2014-01-01

    We have studied the influence of dense whey protein particles on the mechanical properties of whey protein isolate (WPI) gels at high protein concentrations (16–22% (w/w)). Incorporation of dense whey protein particles in the gel, while keeping the total protein concentration constant, leads to a co

  19. VLDL from Metabolic Syndrome Individuals Enhanced Lipid Accumulation in Atria with Association of Susceptibility to Atrial Fibrillation

    Directory of Open Access Journals (Sweden)

    Hsiang-Chun Lee

    2016-01-01

    Full Text Available Metabolic syndrome (MetS represents a cluster of metabolic derangements. Dyslipidemia is an important factor in MetS and is related to atrial fibrillation (AF. We hypothesized that very low density lipoproteins (VLDL in MetS (MetS-VLDL may induce atrial dilatation and vulnerability to AF. VLDL was therefore separated from normal (normal-VLDL and MetS individuals. Wild type C57BL/6 male mice were divided into control, normal-VLDL (nVLDL, and MetS-VLDL (msVLDL groups. VLDL (15 µg/g and equivalent volumes of saline were injected via tail vein three times a week for six consecutive weeks. Cardiac chamber size and function were measured by echocardiography. MetS-VLDL significantly caused left atrial dilation (control, n = 10, 1.64 ± 0.23 mm; nVLDL, n = 7, 1.84 ± 0.13 mm; msVLDL, n = 10, 2.18 ± 0.24 mm; p < 0.0001 at week 6, associated with decreased ejection fraction (control, n = 10, 62.5% ± 7.7%, vs. msVLDL, n = 10, 52.9% ± 9.6%; p < 0.05. Isoproterenol-challenge experiment resulted in AF in young msVLDL mice. Unprovoked AF occurred only in elderly msVLDL mice. Immunohistochemistry showed excess lipid accumulation and apoptosis in msVLDL mice atria. These findings suggest a pivotal role of VLDL in AF pathogenesis for MetS individuals.

  20. Concentrations of ultrafine particles at a highway toll collection booth and exposure implications for toll collectors.

    Science.gov (United States)

    Cheng, Yu-Hsiang; Huang, Cheng-Hsiung; Huang, Hsiao-Lin; Tsai, Chuen-Jinn

    2010-12-15

    Research regarding the magnitude of ultrafine particle levels at highway toll stations is limited. This study measured ambient concentrations of ultrafine particles at a highway toll station from October 30 to November 1 and November 5 to November 6, 2008. A scanning mobility particle sizer was used to measure ultrafine particle concentrations at a ticket/cash tollbooth. Levels of hourly average ultrafine particles at the tollbooth were about 3-6 times higher than those in urban backgrounds, indicating that a considerable amount of ultrafine particles are exhausted from passing vehicles. A bi-modal size distribution pattern with a dominant mode at about particle reactions in fresh fumes emitted directly from vehicles. The influences of traffic volume, wind speed, and relative humidity on ultrafine particle concentrations were also determined. High ambient concentrations of ultrafine particles existed under low wind speed, low relative humidity, and high traffic volume. Although different factors account for high ambient concentrations of ultrafine particles at the tollbooth, measurements indicate that toll collectors who work close to traffic emission sources have a high exposure risk.

  1. Softness of atherogenic lipoproteins: a comparison of very low density lipoprotein (VLDL) and low density lipoprotein (LDL) using elastic incoherent neutron scattering (EINS).

    Science.gov (United States)

    Mikl, Christian; Peters, Judith; Trapp, Marcus; Kornmueller, Karin; Schneider, Wolfgang J; Prassl, Ruth

    2011-08-31

    Apolipoprotein B100 (apoB100)-containing plasma lipoproteins (LDL and VLDL) supply tissues and cells with cholesterol and fat. During lipolytic conversion from VLDL to LDL the size and chemical composition of the particles change, but the apoB100 molecule remains bound to the lipids and regulates the receptor mediated uptake. The molecular physical parameters which control lipoprotein remodeling and enable particle stabilization by apoB100 are largely unknown. Here, we have compared the molecular dynamics and elasticities of VLDL and LDL derived by elastic neutron scattering temperature scans. We have determined thermal motions, dynamical transitions, and molecular fluctuations, which reflect the temperature-dependent motional coupling between lipid and protein. Our results revealed that lipoprotein particles are extremely soft and flexible. We found substantial differences in the molecular resiliences of lipoproteins, especially at higher temperatures. These discrepancies not only can be explained in terms of lipid composition and mobility but also suggest that apoB100 displays different dynamics dependent on the lipoprotein it is bound to. Hence, we suppose that the inherent conformational flexibility of apoB100 permits particle stabilization upon lipid exchange, whereas the dynamic coupling between protein and lipids might be a key determinant for lipoprotein conversion and atherogenicity.

  2. Effect of Theobromine Consumption on Serum Lipoprotein Profiles in Apparently Healthy Humans with Low HDL-Cholesterol Concentrations

    Directory of Open Access Journals (Sweden)

    Doris M. Jacobs

    2017-08-01

    Full Text Available Scope: Theobromine is a major active compound in cocoa with allegedly beneficial effect on high-density-lipoprotein-cholesterol (HDL-CH. We have investigated the effect of theobromine (TB consumption on the concentrations of triglyceride (TG and cholesterol (CH in various lipoprotein (LP subclasses.Methods: In a randomized, double-blind, placebo-controlled, cross-over study, 44 apparently healthy women and men (age: 60 ± 6 years, BMI: 29 ± 3 kg/m2 with low baseline HDL-CH concentrations consumed a drink supplemented with 500 mg/d theobromine for 4 weeks. TG and CH concentrations in 15 LP subclasses were predicted from diffusion-edited 1H NMR spectra of fasting serum.Results: The LP phenotype of the subjects was characterized by low CH concentrations in the large HDL particles and high TG concentrations in large VLDL and chylomicron (CM particles, which clearly differed from a LP phenotype of subjects with normal HDL-CH. TB only reduced CH concentrations in the LDL particles by 3.64 and 6.79%, but had no effect on TG and CH in any of the HDL, VLDL and CM subclasses.Conclusion: TB was not effective on HDL-CH in subjects with a LP phenotype characterized by low HDL-CH and high TG in VLDL.

  3. Characterisation of particle emissions from the driving car fleet and the contribution to ambient and indoor particle concentrations

    Science.gov (United States)

    Palmgren, Finn; Wåhlin, Peter; Kildesø, Jan; Afshari, Alireza; Fogh, Christian L.

    The population is mainly exposed to high air pollution concentrations in the urban environment, where motor vehicle emissions constitute the main source of fine and ultrafine particles. These particles can penetrate deep into the respiratory system, and studies indicate that the smaller the particle, the larger the health impacts. The chemical composition, surface reactivity and physical properties are also important. However, the knowledge about chemical and physical properties of particles and the temporal and spatial variability of the smallest particles is still very limited. The present study summarises the first results of a larger project with the aims to improve the knowledge. The concentration and the emissions of ultrafine particles from petrol and diesel vehicles, respectively, have been quantified using Scanning Mobility Particle Sizer of ultrafine particles in the size range 6-700 nm and routine monitoring data from urban streets and urban background in Denmark. The quantification was carried out using receptor modelling. The number size distributions of petrol and diesel emissions showed a maximum at 20-30 nm and non-traffic at ≈100 nm. The contribution of ultrafine particles from diesel vehicles is dominating in streets. The same technique has been applied on PM 10, and ≈50% contribution from non-traffic. The technique has also been introduced in relation to elemental and organic carbon, and the first data showed strong correlation between traffic pollution and elemental carbon. The outdoor air quality has a significant effect on indoor pollution levels, and we spend most of the time indoors. Knowledge about the influence of ambient air pollution on the concentrations in the indoor environment is therefore crucial for assessment of human health effects of traffic pollution. The results of our studies will be included in air quality models for calculation of human exposure. Preliminary results from our first campaign showed, that the deposition

  4. Very-low-density lipoprotein (VLDL)-producing and hepatitis C virus-replicating HepG2 cells secrete no more lipoviroparticles than VLDL-deficient Huh7.5 cells.

    Science.gov (United States)

    Jammart, Baptiste; Michelet, Maud; Pécheur, Eve-Isabelle; Parent, Romain; Bartosch, Birke; Zoulim, Fabien; Durantel, David

    2013-05-01

    In the plasma samples of hepatitis C virus (HCV)-infected patients, lipoviroparticles (LVPs), defined as (very-) low-density viral particles immunoprecipitated with anti-β-lipoproteins antibodies are observed. This HCV-lipoprotein association has major implications with respect to our understanding of HCV assembly, secretion, and entry. However, cell culture-grown HCV (HCVcc) virions produced in Huh7 cells, which are deficient for very-low-density lipoprotein (VLDL) secretion, are only associated with and dependent on apolipoprotein E (apoE), not apolipoprotein B (apoB), for assembly and infectivity. In contrast to Huh7, HepG2 cells can be stimulated to produce VLDL by both oleic acid treatment and inhibition of the MEK/extracellular signal-regulated kinase (ERK) pathway but are not permissive for persistent HCV replication. Here, we developed a new HCV cell culture model to study the interaction between HCV and lipoproteins, based on engineered HepG2 cells stably replicating a blasticidin-tagged HCV JFH1 strain (JB). Control Huh7.5-JB as well as HepG2-JB cell lines persistently replicated viral RNA and expressed viral proteins with a subcellular colocalization of double-stranded RNA (dsRNA), core, gpE2, and NS5A compatible with virion assembly. The intracellular RNA replication level was increased in HepG2-JB cells upon dimethyl sulfoxide (DMSO) treatment, MEK/ERK inhibition, and NS5A overexpression to a level similar to that observed in Huh7.5-JB cells. Both cell culture systems produced infectious virions, which were surprisingly biophysically and biochemically similar. They floated at similar densities on gradients, contained mainly apoE but not apoB, and were not neutralized by anti-apoB antibodies. This suggests that there is no correlation between the ability of cells to simultaneously replicate HCV as well as secrete VLDL and their capacity to produce LVPs.

  5. Particle concentration and flux dynamics in the atmospheric boundary layer as the indicator of formation mechanism

    Directory of Open Access Journals (Sweden)

    J. Lauros

    2010-08-01

    Full Text Available We carried out column model simulations to study particle fluxes and deposition and to evaluate different particle formation mechanisms at a boreal forest site in Finland. We show that kinetic nucleation of sulphuric acid cannot be responsible for new particle formation alone as the vertical profile of particle number distribution does not correspond to observations. Instead organic induced nucleation leads to good agreement confirming the relevance of the aerosol formation mechanism including organic compounds emitted by biosphere.

    Simulation of aerosol concentration inside the atmospheric boundary layer during nucleation days shows highly dynamical picture, where particle formation is coupled with chemistry and turbulent transport. We have demonstrated suitability of our turbulent mixing scheme in reproducing most important characteristics of particle dynamics inside the atmospheric boundary layer. Deposition and particle flux simulations show that deposition affects noticeably only the smallest particles at the lowest part of the atmospheric boundary layer.

  6. The binding of human lipoprotein lipase treated VLDL by the human hepatoma cell line HepG2

    NARCIS (Netherlands)

    Mulder, M.; Wit, E.de; Havekes, L.M.

    1991-01-01

    It has been suggested that besides the LDL-receptor, hepatocytes possess an apo E or remnant receptor. To evaluate which hepatic lipoprotein receptor is involved in VLDL remnant catabolism, we studied the binding of VLDL remnants to HepG2 cells. Native VLDL was obtained from type IIb hyperlipidemic

  7. LXR agonist increases apoE secretion from HepG2 spheroid, together with an increased production of VLDL and apoE-rich large HDL

    Directory of Open Access Journals (Sweden)

    Koike Kazuhiko

    2011-08-01

    Full Text Available Abstract Background The physiological regulation of hepatic apoE gene has not been clarified, although the expression of apoE in adipocytes and macrophages has been known to be regulated by LXR. Methods and Results We investigated the effect of TO901317, a LXR agonist, on hepatic apoE production utilizing HepG2 cells cultured in spheroid form, known to be more differentiated than HepG2 cells in monolayer culture. Spheroid HepG2 cells were prepared in alginate-beads. The secretions of albumin, apoE and apoA-I from spheroid HepG2 cells were significantly increased compared to those from monolayer HepG2 cells, and these increases were accompanied by increased mRNA levels of apoE and apoA-I. Several nuclear receptors including LXRα also became abundant in nuclear fractions in spheroid HepG2 cells. Treatment with TO901317 significantly increased apoE protein secretion from spheroid HepG2 cells, which was also associated with the increased expression of apoE mRNA. Separation of the media with FPLC revealed that the production of apoE-rich large HDL particles were enhanced even at low concentration of TO901317, and at higher concentration of TO901317, production of VLDL particles increased as well. Conclusions LXR activation enhanced the expression of hepatic apoE, together with the alteration of lipoprotein particles produced from the differentiated hepatocyte-derived cells. HepG2 spheroids might serve as a good model of well-differentiated human hepatocytes for future investigations of hepatic lipid metabolism.

  8. Role of VLDL Receptor in the Process of Foam Cell Formation

    Institute of Scientific and Technical Information of China (English)

    屈伸; 吴凡; 田俊; 李映红; 王燕; 王宇哲; 宗义强

    2004-01-01

    Summary: The role of very low density lipoprotein receptor (LVLDR) in the process of foam cell formation was investigated. After the primary cultured mouse peritoneal macrophages were incubated with VLDL, β-VLDL or low density lipoprotein (LDL), respectively for 24 h and 48 h, foam cells formation was identified by oil red O staining and cellular contents of triglyceride (TG) and total cholesterol (TC) were determined. The mRNA levels of LDLR, LDLR related protein (LRP)and VLDLR were detected by semi-quantitative RT-PCR. The results demonstrated that VLDL, βVLDL and LDL could increase the contents of TG and TC in macrophages. Cells treated with VLDL or β-VLDL showed markedly increased expression of VLDLR and decreased expression of LDLR, whereas LRP was up-regulated slightly. For identifying the effect of VLDL receptor on cellular lipid accumulation, Idl-A7-VR cells, which expresses VLDLR and trace amount of LRP without functional LDLR, was used to incubate with lipoproteins for further examination. The results elucidated that the uptake of triglyceride-rich lipoprotein mediated by VLDLR plays an important role in accumulation of lipid and the formation of foam cells.

  9. Ultrafine particles at eight urban sites in Antwerp. Instrument comparison and spatiotemporal variation in particle number concentration and size distribution

    Energy Technology Data Exchange (ETDEWEB)

    Staelens, J.; Matheeussen, C.; Roekens, E. [Department Air, Environment and Communication, Flemish Environment Agency VMM, Antwerp, 2000 (Belgium); Frijns, E.; Berghmans, P. [Flemish Institute for Technological Research VITO, Mol, 2400 (Belgium); Kos, G.P.A.; Weijers, E.P. [Environment and Energy Engineering, Energy research Centre of the Netherlands ECN, Petten, 1755 ZG (Netherlands); Panteliadis, P. [Department of Air Quality, Public Health Service ofAmsterdam, Amsterdam, 1000 CE (Netherlands); Bergmans, B. [Air Quality, Institut Scientifique de Service Public (ISSeP), Liege, 4000 (Belgium); Wyche, K. [Department of Chemistry, University of Leicester, Leicester, LE2 7TG (United Kingdom)

    2013-03-15

    Due to the short atmospheric lifetime of ultrafine particles (UFP) and their strong dependence on local sources, ambient particle number concentrations and size distributions may vary significantly on short spatial and temporal scales. Because UFP are a primary pollutant that is rapidly transformed by physicochemical processes (dispersion, coagulation, deposition, etc.) and emitted mainly by mobile sources, they show a very high spatial variation. The particle number concentration is known to be elevated near roads and to decrease with increasing distance to the road primarily as a result of dispersion. Therefore, UFP measurements at a single urban background air quality monitoring station may not be indicative of the actual exposure in the communities surrounding this station. To address this problem and to more accurately estimate human exposure and subsequent health impacts of UFP, more intensive measurements on finer spatial scales are needed. Therefore, UFP measurements were carried out at eight urban background or hotspot sites in the city of Antwerp (Belgium)

  10. Shear-induced particle diffusion and its effects on the flow of concentrated suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Acrivos, A. [City College of CUNY, New York, NY (United States)

    1996-12-31

    The mechanism underlying shear-induced particle diffusion in concentrated suspensions is clarified. Examples are then presented where this diffusion process plays a crucial role in determining the manner by which such suspensions flow under laminar conditions.

  11. Luminescent Solar Concentrators Fabricated by Dispersing Rare Earth Particles in PMMA Waveguide

    Directory of Open Access Journals (Sweden)

    Cheng Liu

    2014-01-01

    Full Text Available Luminescent solar concentrators (LSCs were fabricated by dispersing CaAlSiN3 : Eu2+ particles in a PMMA waveguide. A series of LSCs (dimension 5.0 cm × 5.0 cm × 0.5 cm with different CaAlSiN3 : Eu2+ particle concentration were obtained and their performance was evaluated. The maximum optical concentration ratio is 1.23 with a power conversion efficiency of 1.44% for the LSC containing 0.5 wt% CaAlSiN3 : Eu2+ particles concentration. This strategy of dispersing rare earth particles in PMMA waveguide represents an alternative approach to producing highly durable LSCs.

  12. Continuum modeling of hydrodynamic particle–particle interactions in microfluidic high-concentration suspensions

    DEFF Research Database (Denmark)

    Ley, Mikkel Wennemoes Hvitfeld; Bruus, Henrik

    2016-01-01

    A continuum model is established for numerical studies of hydrodynamic particle–particle interactions in microfluidic high-concentration suspensions. A suspension of microparticles placed in a microfluidic channel and influenced by an external force, is described by a continuous particle...

  13. Tire-tread and bitumen particle concentrations in aerosol and soil samples

    DEFF Research Database (Denmark)

    Fauser, Patrik; Tjell, Jens Christian; Mosbæk, Hans;

    2002-01-01

    ire and bitumen particle concentrations are determined in aerosol and soil samples. They each constitute about 5 wt-% of the total suspended particulate matter (TSP) in inner city air, collected with a Berner low pressure impactor, 5 m from a road. The particle size distribution shows that 92% of...

  14. Emission of submicron aerosol particles in cement kilns: Total concentration and size distribution.

    Science.gov (United States)

    Rotatori, Mauro; Mosca, Silvia; Guerriero, Ettore; Febo, Antonio; Giusto, Marco; Montagnoli, Mauro; Bianchini, Massimo; Ferrero, Renato

    2015-01-01

    Cement plants are responsible for particle and gaseous emissions into the atmosphere. With respect to particle emission, the greater part of is in the range from 0.05 to 5.0 µm in diameter. In the last years attention was paid to submicron particles, but there is a lack of available data on the emission from stationary sources. In this paper, concentration and size distribution of particles emitted from four cement kilns, in relationship to operational conditions (especially the use of alternative fuel to coal) of the clinker process are reported. Experimental campaigns were carried out by measuring particles concentration and size distribution at the stack of four cement plants through condensation particle counter (CPC) and scanning mobility particle sizer spectrometer (SMPS). Average total particle number concentrations were between 2000 and 4000 particles/cm³, about 8-10 times lower that those found in the corresponding surrounding areas. As for size distribution, for all the investigated plants it is stable with a unimodal distribution (120-150 nm), independent from the fuel used.

  15. Real-time measurement of aerosol particle concentration at high temperatures; Hiukkaspitoisuuden reaaliaikainen mittaaminen korkeassa laempoetilassa

    Energy Technology Data Exchange (ETDEWEB)

    Keskinen, J.; Hautanen, J.; Laitinen, A. [Tampere Univ. of Technology (Finland). Physics

    1997-10-01

    The aim of this project is to develop a new method for continuous aerosol particle concentration measurement at elevated temperatures (up to 800-1000 deg C). The measured property of the aerosol particles is the so called Fuchs surface area. This quantity is relevant for diffusion limited mass transfer to particles. The principle of the method is as follows. First, aerosol particles are charged electrically by diffusion charging process. The charging takes place at high temperature. After the charging, aerosol is diluted and cooled. Finally, aerosol particles are collected and the total charge carried by the aerosol particles is measured. Particle collection and charge measurement take place at low temperature. Benefits of this measurement method are: particles are charged in-situ, charge of the particles is not affected by the temperature and pressure changes after sampling, particle collection and charge measurement are carried out outside the process conditions, and the measured quantity is well defined. The results of this study can be used when the formation of the fly ash particles is studied. Another field of applications is the study and the development of gasification processes. Possibly, the method can also be used for the monitoring the operation of the high temperature particle collection devices. (orig.)

  16. Radon in indoor concentrations and indoor concentrations of metal dust particles in museums and other public buildings.

    Science.gov (United States)

    Carneiro, G L; Braz, D; de Jesus, E F; Santos, S M; Cardoso, K; Hecht, A A; Dias da Cunha, Moore K

    2013-06-01

    The aim of this study was to evaluate the public and occupational exposure to radon and metal-bearing particles in museums and public buildings located in the city of Rio de Janeiro, Brazil. For this study, four buildings were selected: two historic buildings, which currently house an art gallery and an art museum; and two modern buildings, a chapel and a club. Integrated radon concentration measurements were performed using passive radon detectors with solid state nuclear track detector-type Lexan used as nuclear track detector. Air samplers with a cyclone were used to collect the airborne particle samples that were analyzed by the particle-induced X-ray emission technique. The average unattached-radon concentrations in indoor air in the buildings were above 40 Bq/m(3), with the exception of Building D as measured in 2009. The average radon concentrations in indoor air in the four buildings in 2009 were below the recommended reference level by World Health Organization (100 Bq/m(3)); however, in 2011, the average concentrations of radon in Buildings A and C were above this level, though lower than 300 Bq/m(3). The average concentrations of unattached radon were lower than 148 Bq/m(3) (4pCi/L), the USEPA level recommended to take action to reduce the concentrations of radon in indoor air. The unattached-radon average concentrations were also lower than the value recommended by the European Union for new houses. As the unattached-radon concentrations were below the international level recommended to take action to reduce the radon concentration in air, it was concluded that during the period of sampling, there was low risk to human health due to the inhalation of unattached radon in these four buildings.

  17. Wood dust particle and mass concentrations and filtration efficiency in sanding of wood materials.

    Science.gov (United States)

    Welling, Irma; Lehtimäki, Matti; Rautio, Sari; Lähde, Tero; Enbom, Seppo; Hynynen, Pasi; Hämeri, Kaarle

    2009-02-01

    The importance of fine particles has become apparent as the knowledge of their effects on health has increased. Fine particle concentrations have been published for outside air, plasma arc cutting, welding, and grinding, but little data exists for the woodworking industry. Sanding was evaluated as the producer of the woodworking industry's finest particles, and was selected as the target study. The number of dust particles in different particle size classes and the mass concentrations were measured in the following environments: workplace air during sanding in plywood production and in the inlet and return air; in the dust emission chamber; and in filter testing. The numbers of fine particles were low, less than 10(4) particles/cm(3) (10(7) particles/L). They were much lower than typical number concentrations near 10(6) particles/cm(3) measured in plasma arc cutting, grinding, and welding. Ultrafine particles in the size class less than 100 nm were found during sanding of MDF (medium density fiberboard) sheets. When the cleaned air is returned to the working areas, the dust content in extraction systems must be monitored continuously. One way to monitor the dust content in the return air is to use an after-filter and measure pressure drop across the filter to indicate leaks in the air-cleaning system. The best after-filtration materials provided a clear increase in pressure drop across the filter in the loading of the filter. The best after-filtration materials proved to be quite effective also for fine particles. The best mass removal efficiencies for fine particles around 0.3 mum were over 80% for some filter materials loaded with sanding wood dust.

  18. NUMBER CONCENTRATION, SIZE DISTRIBUTION AND FINE PARTICLE FRACTION OF TROPOSPHERIC AND STRATOSPHERIC AEROSOLS

    Institute of Scientific and Technical Information of China (English)

    Li Xu; Guangyu Shi; Li Zhang; Jun Zhou; Yasunobu Iwasaka

    2003-01-01

    Aerosol observations were carried out at Xianghe Scientific Balloon Base (39.45°N, 117°E) using a stratospheric balloon. The particle number concentrations of the tropospheric and stratospheric aerosols were directly explored.The vertical distributions of the number concentration, number-size (that is, particle number versus particle size)distribution, and the fraction of fine particles (0.5 μm>r>0.15 μm/r>0.15 μm) are reported in this paper. The profiles of particle concentration present multi-peak phenomenon. The pattern of size distribution for atmospheric aerosol indicates a tri-modal (r=~0.2 μm, ~0.88 μm and ~7.0 μm) and a bi-modal (r=~0.13 μm and 2.0 μm). The number-size distribution almost fits the Junge distribution for particles with r<0.5 μm in the stratosphere of 1993 and the troposphere of 1994. But the distributions of coarse particles (r>0.5 μm) are not uniform. The number-size distribution exhibits also a wide size range in the troposphere of 1993. The results demonstrate that fine particles represent the major portion in the troposphere during the measurement period, reaching as high as 95% in 1994. Certain coarse particle peaks in the troposphere were attributed to clouds and other causes, and in the stratosphere to volcanic eruption. The stratospheric aerosol layer consists of unique fractions of fine or coarse particles depending on their sources. In summary, the process of gas-to-particles conversion was active and the coarse particles were rich over the Xianghe area. The measurements also demonstrate that the spatial and temporal atmospheric aerosol distributions are nonuniform and changeful.

  19. PARTICLE CONCENTRATIONS IN A CHURCH DURING DIFFERENT WEATHER CONDITIONS – A CASE STUDY

    OpenAIRE

    Bernard Polednik; Aleksandra Polednik

    2016-01-01

    The purpose of this study is to report particle number (PN) and particle mass (PM) concentration changes in the church during three 60-minute Masses held on a cloudy, sunny and rainy day. At each Mass with a similar number of participants the same number of candles was lit and incense was burned. The highest average PN1 and PM1 concentrations of submicrometer particles which respectively amounted to 23.9 pt/cm3 and 241.1 µg/m3 were obtained for the Mass held on a rainy day. During that Mass t...

  20. Effect of Particle Concentration on Ablation Behavior of Carbon/Carbon Composites

    Directory of Open Access Journals (Sweden)

    ZHA Bai-lin

    2016-07-01

    Full Text Available A self-designed oxygen-kerosene ablation system was employed to study the ablation mechanism and performance of the carbon-carbon composites. Particle concentrations of the gas-solid two-phase ablation flow were 0, 1.37%, 2.22%, and 2.64% respectively. The microstructure of post-test samples was analysed through the scanning electron microscope (SEM, and the ablation rate was calculated. The influence principle of particle concentrations on the ablation rate of the carbon-carbon composites was studied, and the mechanism of ablation was analysed. Experiment results show that with no particles involved the mass ablation rate is 0.159g/s and the linear ablation rate is 0.175mm/s, while with particles introduced, the minimum mass ablation rate and linear ablation rate are 0.432g/s and 0.843mm/s respectively, with the increase of particle concentrations, the ablation rate becomes accelerated. Particle erosion makes the ablation of sample seriously intensified, and the ablation gradient of radial fiber on erosion surface is increased with the increase of particle concentrations as well.

  1. GLP-1 receptor agonism ameliorates hepatic VLDL overproduction and de novo lipogenesis in insulin resistance

    Directory of Open Access Journals (Sweden)

    Jennifer Taher

    2014-12-01

    Conclusion: Exendin-4 prevents fructose-induced dyslipidemia and hepatic VLDL overproduction in insulin resistance through an indirect mechanism involving altered energy utilization, decreased hepatic lipid synthesis and also requires an intact parasympathetic signaling pathway.

  2. Increased VLDL-TG fatty acid storage in skeletal muscle in men with type 2 diabetes

    DEFF Research Database (Denmark)

    Andersen, Iben R; Søndergaard, Esben; Sørensen, Lars P

    2016-01-01

    -TG storage rate and LPL activity or other storage factors in muscle or adipose tissue. However, LPL activity correlated with fractional VLDL-TG storage in abdominal fat (p=0.04). CONCLUSIONS: Men with type 2 diabetes have increased VLDL-TG storage in muscle tissue, potentially contributing to increased......CONTEXT: Lipoprotein lipase (LPL) activity is considered the rate-limiting step of very-low-density-lipoprotein triglycerides (VLDL-TG) tissue storage, and has been suggested to relate to the development of obesity as well as insulin resistance and type 2 diabetes. OBJECTIVE: The objective...... of the study was to assess the relationship between the quantitative storage of VLDL-TG fatty acids and LPL activity and other storage factors in muscle and adipose tissue. In addition, we examine whether such relations were influenced by type 2 diabetes. DESIGN: 23 men (12 with type 2 diabetes, 11 non...

  3. Modeling Particle Concentration In Slurry Flows Using Shear-Induced Migration: Theory vs. Experiments

    Science.gov (United States)

    Lin, Kanhui; Latterman, Paul; Koch, Trystan; Hu, Vincent; Ho, Joyce; Mata, Matthew; Murisic, Nebojsa; Bertozzi, Andrea

    2009-11-01

    Different flow regimes observed in our experimental study of particle-laden thin film flows are characterized by differing particle concentration profiles. We develop a theoretical model for particle concentration in order to capture our experimental observations. Our model is based on equilibrium assumption and it incorporates all relevant physical mechanisms, including shear-induced particle migration and settling due to gravity. It leads to a coupled system of ordinary differential equations for particle volume fraction and shear, which are solved numerically for various parameter sets. We find excellent agreement between our numerical results and experimental data. Our model is not only successful in reproducing the experimentally observed regimes, but also in capturing the connection between these regimes and the experimental parameters.

  4. Water Condensation Growth Cells for Ultrafine Particle Collection Onto Concentrated Spots

    Science.gov (United States)

    Lewis, G. S.; Hering, S. V.; Kreisberg, N.

    2007-12-01

    A laminar flow, condensation method, analogous to that employed in the water-based condensation particle counters, is utilized to provide concentrated, low-pressure drop collection of fine and ultrafine particles. With the laminar flow water condensation approach, the aerosol flow is first chilled by a cold walled conditioner, and then introduced into a hot wet-walled condenser. Because water vapor diffuses more rapidly then heat, the air vapor is supersaturated resulting in particles large enough to be collected by impaction. Several types of collectors have been designed and tested. A compact system utilizing a single TED as a heat pump to provide a ~ 25 ° C temperature difference provides collection at 0.4 L/min with a lower cutpoint of 10 nm, a pressure drop of 1 kPa, and a power consumption of 1 Watt. A larger, parallel plate system samples at 10 L/min, and yields a cutpoint of 20 nm. The design of these systems was guided by numeric modeling of the saturation ratios, particle activation and growth. The model includes the heat release from condensation, and the associated warming of the flow that reduces the supersaturation and particle growth at high particle number concentrations. By controlling the system geometry (either plate separation or tube diameter), we are able to activate at small particle sizes while minimizing concentration effects. Our method of particle collection provides a number of other advantages. Particle bounce off the impaction surface can be eliminated by controlling the temperature of the impaction surface so as to maintain a thin film of water on the surface. Particles can also be collected into a small liquid vial containing less then 1 ml of fluid, which eliminates the need for particle extraction from filters or resuspension from surface, it minimizes the total volume of the sample, and it allows for continuous automated collection and analysis.

  5. Investigation of particle inertial migration in high particle concentration suspension flow by multi-electrodes sensing and Eulerian-Lagrangian simulation in a square microchannel.

    Science.gov (United States)

    Zhao, Tong; Yao, Jiafeng; Liu, Kai; Takei, Masahiro

    2016-03-01

    The inertial migration of neutrally buoyant spherical particles in high particle concentration (αpi  > 3%) suspension flow in a square microchannel was investigated by means of the multi-electrodes sensing method which broke through the limitation of conventional optical measurement techniques in the high particle concentration suspensions due to interference from the large particle numbers. Based on the measured particle concentrations near the wall and at the corner of the square microchannel, particle cross-sectional migration ratios are calculated to quantitatively estimate the migration degree. As a result, particle migration to four stable equilibrium positions near the centre of each face of the square microchannel is found only in the cases of low initial particle concentration up to 5.0 v/v%, while the migration phenomenon becomes partial as the initial particle concentration achieves 10.0 v/v% and disappears in the cases of the initial particle concentration αpi  ≥ 15%. In order to clarify the influential mechanism of particle-particle interaction on particle migration, an Eulerian-Lagrangian numerical model was proposed by employing the Lennard-Jones potential as the inter-particle potential, while the inertial lift coefficient is calculated by a pre-processed semi-analytical simulation. Moreover, based on the experimental and simulation results, a dimensionless number named migration index was proposed to evaluate the influence of the initial particle concentration on the particle migration phenomenon. The migration index less than 0.1 is found to denote obvious particle inertial migration, while a larger migration index denotes the absence of it. This index is helpful for estimation of the maximum initial particle concentration for the design of inertial microfluidic devices.

  6. Particle concentrations and number size distributions in the planetary boundary layer derived from airship based measurements

    Science.gov (United States)

    Tillmann, Ralf; Zhao, Defeng; Ehn, Mikael; Hofzumahaus, Andreas; Holland, Frank; Rohrer, Franz; Kiendler-Scharr, Astrid; Wahner, Andreas

    2014-05-01

    Atmospheric particles play a key role for regional and global climate due to their direct and indirect radiative forcing effects. The concentration and size of the particles are important variables to these effects. Within the continental planetary boundary layer (PBL) the particle number size distribution is influenced by meteorological parameters, local sinks and sources resulting in variable spatial distributions. However, measurements of particle number size distributions over a broad vertical range of the PBL are rare. The airship ZEPPELIN NT is an ideal platform to measure atmospheric aerosols on a regional scale within an altitude range up to 1000 m. For campaigns in the Netherlands, Northern Italy and South Finland in 2012 and 2013 the airship was deployed with a wide range of instruments, including measurements of different trace gases, short lived radicals, solar radiation, aerosols and meteorological parameters. Flights were carried out at different times of the day to investigate the influence of the diurnal evolution of the PBL on atmospheric trace gases and aerosols. During night and early morning hours the concentration and size distribution of atmospheric particles were found to be strongly influenced by the layered structure of the PBL, i.e. the nocturnal boundary layer and the residual layer. Within the residual layer particle concentrations stay relatively constant as this layer is decoupled from ground sources. The particles persist in the accumulation mode as expected for an aged aerosol. In the nocturnal boundary layer particle concentrations and size are more dynamic with higher concentrations than in the residual layer. A few hours after sunrise, the layered structure of the PBL intermixes. During daytime the PBL is well mixed and a negative concentration gradient with increasing height is observed. Several height profiles at different times of the day and at different locations in Europe were measured. The aerosol measurements will be

  7. A miniature system for separating aerosol particles and measuring mass concentrations.

    Science.gov (United States)

    Liang, Dao; Shih, Wen-Pin; Chen, Chuin-Shan; Dai, Chi-An

    2010-01-01

    We designed and fabricated a new sensing system which consists of two virtual impactors and two quartz-crystal microbalance (QCM) sensors for measuring particle mass concentration and size distribution. The virtual impactors utilized different inertial forces of particles in air flow to classify different particle sizes. They were designed to classify particle diameter, d, into three different ranges: d3.20 μm. The QCM sensors were coated with a hydrogel, which was found to be a reliable adhesive for capturing aerosol particles. The QCM sensor coated with hydrogel was used to measure the mass loading of particles by utilizing its characteristic of resonant frequency shift. An integrated system has been demonstrated.

  8. A Miniature System for Separating Aerosol Particles and Measuring Mass Concentrations

    Directory of Open Access Journals (Sweden)

    Dao Liang

    2010-04-01

    Full Text Available We designed and fabricated a new sensing system which consists of two virtual impactors and two quartz-crystal microbalance (QCM sensors for measuring particle mass concentration and size distribution. The virtual impactors utilized different inertial forces of particles in air flow to classify different particle sizes. They were designed to classify particle diameter, d, into three different ranges: d < 2.28 μm, 2.28 μm ≤ d ≤ 3.20 μm, d > 3.20 μm. The QCM sensors were coated with a hydrogel, which was found to be a reliable adhesive for capturing aerosol particles. The QCM sensor coated with hydrogel was used to measure the mass loading of particles by utilizing its characteristic of resonant frequency shift. An integrated system has been demonstrated.

  9. The effect of inorganic particle concentration on bacteria-virus-nanoflagellate dynamics.

    Science.gov (United States)

    Salter, Ian; Böttjer, Daniela; Christaki, Urania

    2011-10-01

    The effect of inorganic particle concentrations on bacteria-virus-nanoflagellate dynamics in an oligotrophic coastal system was investigated using a model aluminosilicate, kaolinite, with a modal size of 2.1 µm. Virus-only, bacteria-only and bacteria-virus-nanoflagellate incubations were carried out at increasing kaolinite concentrations to elucidate the microbial response. The sorption of bacteria and viruses to kaolinite particles was negligible over a concentration range of 1-50 mg l(-1). In contrast, the abundance of heterotrophic nanoflagellates was negatively correlated with kaolinite concentrations following both 48 and 96 h incubations. Calculated nanoflagellate bacterial ingestion rates were reduced by 5-35% depending on kaolinite particle concentration. In the bacteria-virus-nanoflagellate incubations viral production increased by 56 × 10(3) to 104 × 10(3) VLPs ml(-1) h(-1) as a function of kaolinite particle concentration. Our results demonstrate for the first time that the interaction of microbial populations with inorganic particles can shift the balance between protist and virally mediated mortality of marine heterotrophic prokaryotes. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  10. Factors affecting the association between ambient concentrations and personal exposures to particles and gases.

    Science.gov (United States)

    Sarnat, Stefanie Ebelt; Coull, Brent A; Schwartz, Joel; Gold, Diane R; Suh, Helen H

    2006-05-01

    Results from air pollution exposure assessment studies suggest that ambient fine particles [particulate matter with aerodynamic diameterpersonal exposures. For particles, the strength of the personal-ambient association can differ by particle component and level of home ventilation. For gases, however, such as ozone (O3), nitrogen dioxide (NO2), and sulfur dioxide (SO2), the impact of home ventilation on personal-ambient associations is untested. We measured 24-hr personal exposures and corresponding ambient concentrations to PM2.5, sulfate (SO2-(4)), elemental carbon, O3, NO2, and SO2 for 10 nonsmoking older adults in Steubenville, Ohio. We found strong associations between ambient particle concentrations and corresponding personal exposures. In contrast, although significant, most associations between ambient gases and their corresponding exposures had low slopes and R2 values; the personal-ambient NO2 association in the fall season was moderate. For both particles and gases, personal-ambient associations were highest for individuals spending most of their time in high- compared with low-ventilated environments. Cross-pollutant models indicated that ambient particle concentrations were much better surrogates for exposure to particles than to gases. With the exception of ambient NO2 in the fall, which showed moderate associations with personal exposures, ambient gases were poor proxies for both gas and particle exposures. In combination, our results suggest that a) ventilation may be an important modifier of the magnitude of effect in time-series health studies, and b) results from time-series health studies based on 24-hr ambient concentrations are more readily interpretable for particles than for gases.

  11. Analysis of particle-borne odorants emitted from concentrated animal feeding operations.

    Science.gov (United States)

    Yang, Xufei; Lorjaroenphon, Yaowapa; Cadwallader, Keith R; Wang, Xinlei; Zhang, Yuanhui; Lee, Jongmin

    2014-08-15

    Airborne particles are known to serve as a carrier of odors emanating from concentrated animal feeding operations (CAFOs). However, limited quantitative data about particle-borne odorants preclude an accurate assessment of the role of particles in odor transport. This study collected total suspended particulates (TSP) and PM10 (particles with aerodynamic diameter smaller than 10 μm) at the air exhaust of eight types of CAFOs (swine: farrowing, gestation, weaning, and finishing; poultry: manure-belt layer hen, tom turkey, chicken broiler, and cage-free layer hen; in total 20 animal buildings) in multiple seasons, and examined the variability in particle odorant composition with animal operation type, season, and particle size. Fifty-seven non-sulfur-containing odorants were identified and quantitated, including carbonyls, alcohols, acids, phenols, and nitrogen-containing compounds. They in total accounted for 2.19±1.52% TSP and 4.97±3.25% PM10 mass. Acetic acid and ethanol were most abundant but less odor-contributing than phenylacetic acid, indole, dodecanoic acid, and (E,E)-2,4-decadienal, as determined by odor activity value. Particle odorant composition varied significantly with animal operation type, season, and particle size. The TSP and PM10 samples from swine gestation buildings, for example, showed distinctly different odorant compositions than those from tom turkey buildings. The summer TSP and PM10 samples contained in general lower concentrations of short-chain fatty acids but higher concentrations of long-chain fatty acids, aldehydes, and short-chain alcohols than the winter samples. Compared to TSP, PM10 samples from different types of CAFOs shared a more similar odorant composition, contained higher odorant concentrations per mass of particles, and accounted for on average 53.2% of the odor strength of their corresponding TSP samples.

  12. Concentrations of inertial particles in the turbulent wake of an immobile sphere

    CERN Document Server

    Homann, Holger

    2015-01-01

    Direct numerical simulations are used to study the interaction of a stream of small heavy inertial particles with the laminar and turbulent wakes of an immobile sphere facing an incompressible uniform inflow. Particles that do not collide with the obstacle but move past it, are found to form preferential concentrations both in the sphere boundary layer and in its wake. In the laminar case, the upstream diverging flow pattern is responsible for particle clustering on a cylinder that extends far downstream the sphere. The interior of this surface contains no particles and can be seen as a shadow of the large obstacle. Such concentration profiles are also present in the case of turbulent wakes but show a finite extension. The sphere shadow is followed by a region around the axis of symmetry where the concentration is higher than the average. It originates from a resonant centrifugal expulsion of particles from shed vortices. The consequence of this concentration mechanism on monodisperse inter-particle collision...

  13. Primary versus secondary contributions to particle number concentrations in the European boundary layer

    Directory of Open Access Journals (Sweden)

    C. L. Reddington

    2011-12-01

    Full Text Available It is important to understand the relative contribution of primary and secondary particles to regional and global aerosol so that models can attribute aerosol radiative forcing to different sources. In large-scale models, there is considerable uncertainty associated with treatments of particle formation (nucleation in the boundary layer (BL and in the size distribution of emitted primary particles, leading to uncertainties in predicted cloud condensation nuclei (CCN concentrations. Here we quantify how primary particle emissions and secondary particle formation influence size-resolved particle number concentrations in the BL using a global aerosol microphysics model and aircraft and ground site observations made during the May 2008 campaign of the European Integrated Project on Aerosol Cloud Climate Air Quality Interactions (EUCAARI. We tested four different parameterisations for BL nucleation and two assumptions for the emission size distribution of anthropogenic and wildfire carbonaceous particles. When we emit carbonaceous particles at small sizes (as recommended by the Aerosol Intercomparison project, AEROCOM, the spatial distributions of campaign-mean number concentrations of particles with diameter >50 nm (N50 and >100 nm (N100 were well captured by the model (R2≥0.8 and the normalised mean bias (NMB was also small (−18% for N50 and −1% for N100. Emission of carbonaceous particles at larger sizes, which we consider to be more realistic for low spatial resolution global models, results in equally good correlation but larger bias (R2≥0.8, NMB = −52% and −29%, which could be partly but not entirely compensated by BL nucleation. Within the uncertainty of the observations and accounting for the uncertainty in the size of emitted primary particles, BL nucleation makes a statistically significant contribution to CCN

  14. Ethnic differences in serum lipids and lipoproteins in overweight/obese African-American and white American women with pre-diabetes: significance of NMR-derived lipoprotein particle concentrations and sizes.

    Science.gov (United States)

    Gaillard, Trudy; Osei, Kwame

    2016-01-01

    African-American women (AAW) suffer disproportionately from higher rates of cardiovascular disease (CVD) mortality compared with white American women (WAW), despite favorable lipid and lipoprotein profile. Therefore, we used nuclear magnetic resonance (NMR) to examine lipoprotein particle concentrations and sizes in overweight/obese AAW and WAW with pre-diabetes. We studied 69 AAW and 41 WAW, with mean age 46.5±11.3 years and body mass index (BMI) 37.8±6.4 kg/m(2). All participants completed standard oral glucose tolerance test (OGTT) and frequently sampled intravenous glucose tolerance test (FSIVGTT). Insulin sensitivity (Si) was calculated using MINIMOD method. Body composition was assessed using dual-energy X-ray absorptiometry (DEXA). Fasting blood was obtained for traditional lipids/lipoproteins and NMR-derived lipoprotein particle sizes and concentrations. We found that AAW with pre-diabetes were more obese (BMI 38.8±6.7 vs 36.0±5.4 kg/m(2), p=0.02) than WAW. Mean Si was not significantly different. However, the mean serum triglycerides were lower, whereas the high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A1 (Apo A1) were significantly higher in AAW versus WAW. The large HDL particle concentration (6.1±3.1 vs 4.6±3.1 µmol/L, p=0.02) was significantly higher in AAW versus WAW. Mean total very low-density lipoprotein (VLDL) particle concentration was lower in AAW versus WAW (39.9±24.4 vs 59.2±25.6 nmol/L, p≤0.001). While mean total LDL particle concentrations were not different, mean small LDL particle concentrations were lower in AAW versus WAW (538.8±294.1 vs 638.4±266 nmol/L, p=0.07). We found a more favorable NMR-derived lipoprotein profile in AAW that extends the traditional antiatherogenic lipid/lipoprotein profiles. Clinically, these favorable lipid/lipoprotein profiles cannot explain the paradoxically higher CVD mortality in AAW than WAW and warrant further prospective outcome studies.

  15. Ethnic differences in serum lipids and lipoproteins in overweight/obese African-American and white American women with pre-diabetes: significance of NMR-derived lipoprotein particle concentrations and sizes

    Science.gov (United States)

    Gaillard, Trudy; Osei, Kwame

    2016-01-01

    Objective African-American women (AAW) suffer disproportionately from higher rates of cardiovascular disease (CVD) mortality compared with white American women (WAW), despite favorable lipid and lipoprotein profile. Therefore, we used nuclear magnetic resonance (NMR) to examine lipoprotein particle concentrations and sizes in overweight/obese AAW and WAW with pre-diabetes. Participants and methods We studied 69 AAW and 41 WAW, with mean age 46.5±11.3 years and body mass index (BMI) 37.8±6.4 kg/m2. All participants completed standard oral glucose tolerance test (OGTT) and frequently sampled intravenous glucose tolerance test (FSIVGTT). Insulin sensitivity (Si) was calculated using MINIMOD method. Body composition was assessed using dual-energy X-ray absorptiometry (DEXA). Fasting blood was obtained for traditional lipids/lipoproteins and NMR-derived lipoprotein particle sizes and concentrations. Results We found that AAW with pre-diabetes were more obese (BMI 38.8±6.7 vs 36.0±5.4 kg/m2, p=0.02) than WAW. Mean Si was not significantly different. However, the mean serum triglycerides were lower, whereas the high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A1 (Apo A1) were significantly higher in AAW versus WAW. The large HDL particle concentration (6.1±3.1 vs 4.6±3.1 µmol/L, p=0.02) was significantly higher in AAW versus WAW. Mean total very low-density lipoprotein (VLDL) particle concentration was lower in AAW versus WAW (39.9±24.4 vs 59.2±25.6 nmol/L, p≤0.001). While mean total LDL particle concentrations were not different, mean small LDL particle concentrations were lower in AAW versus WAW (538.8±294.1 vs 638.4±266 nmol/L, p=0.07). Conclusions We found a more favorable NMR-derived lipoprotein profile in AAW that extends the traditional antiatherogenic lipid/lipoprotein profiles. Clinically, these favorable lipid/lipoprotein profiles cannot explain the paradoxically higher CVD mortality in AAW than WAW and warrant further

  16. Retention and transport of silica nanoparticles in saturated porous media: effect of concentration and particle size.

    Science.gov (United States)

    Wang, Chao; Bobba, Aparna Devi; Attinti, Ramesh; Shen, Chongyang; Lazouskaya, Volha; Wang, Lian-Ping; Jin, Yan

    2012-07-03

    Investigations on factors that affect the fate and transport of nanoparticles (NPs) remain incomplete to date. In the present study, we conducted column experiments using 8 and 52 nm silica NPs to examine the effects of NPs' concentration and size on their retention and transport in saturated porous media. Results showed that higher particle number concentration led to lower relative retention and greater surface coverage. Smaller NPs resulted in higher relative retention and lower surface coverage. Meanwhile, evaluation of size effect based on mass concentration (mg/L) vs particle number concentration (particles/mL) led to different conclusions. A set of equations for surface coverage calculation was developed and applied to explain the different results related to the size effects when a given mass concentration (mg/L) and a given particle number concentration were used. In addition, we found that the retained 8 nm NPs were released upon lowered solution ionic strength, contrary to the prediction by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The study herein highlights the importance of NPs' concentration and size on their behavior in porous media. To the best of our knowledge, it is the first report of an improved equation for surface coverage calculation using column breakthrough data.

  17. KINETIC MODELING OF CONSTITUTIVE RELATIONS FOR PARTICLE MOTION IN LOW TO MODERATELY CONCENTRATED FLOWS

    Institute of Scientific and Technical Information of China (English)

    Guangqian WANG; Xudong FU; Xingkui WANG

    2005-01-01

    Formulating underlying mechanisms of concentrated solid-liquid flows is essential for simulation of various industrial processes and natural phenomena. A generalized constitutive model for particle motion in flows with low to moderate solids concentrations is developed. This generalized model facilitates characterization of inelastic collisions, particle-fluid interactions, and shearing effects.Moderately concentrated simple shear flows of a sand-water mixture are analyzed, and comparisons of model predictions and experimental data are in good agreement. This model exhibits sound performance in characterizing particle motion for wide ranges of concentration and shear rate, and may supply a reasonable and competent alternative to previous models developed for dilute and rapid-granular flows when applied to moderately concentrated situations. The concentration approaches zero (C → 0) asymptote is observed at a relatively high shear rate in model predictions.Assumption of low collisional dissipation of the particle phase as C → 0 is more reasonable for this observation, compared to that without the interstitial fluid effect. Accurately modeling energy dissipation is important for characterizing the stability of dilute simple shear flows of solid-liquid mixtures. Incorporating friction forces will also facilitate improvement of the applicability of this generalized model to flows at extremely high concentrations.

  18. Giant In-Particle Field Concentration and Fano Resonances at Light Scattering by High-Refractive Index Particles

    CERN Document Server

    Tribelsky, M I

    2015-01-01

    A detailed analytical inspection of light scattering by a particle with high refractive index m+i\\kappa and small dissipative constant \\kappa is presented. We have shown that there is a dramatic difference in the behavior of the electromagnetic field within the particle (inner problem) and the scattered field outside it (outer problem). With an increase in m at fix values of the other parameters, the field within the particle asymptotically converges to a periodic function of m. The electric and magnetic type Mie resonances of different orders overlap substantially. It may lead to a giant concentration of the electromagnetic energy within the particle. At the same time, we demonstrate that identical transformations of the solution for the outer problem allow to present each partial scattered wave as a sum of two partitions. One of them corresponds to the m-independent wave, scattered by a perfectly reflecting particle and plays the role of a background, while the other is associated with the excitation of a s...

  19. [Concentration and Particle Size Distribution of Microbiological Aerosol During Haze Days in Beijing].

    Science.gov (United States)

    Hu, Ling-fei; Zhang, Ke; Wang, Hong-bao; Li, Na; Wang, Jie; Yang, Wen-hui; Yin, Zhe; Jiao, Zhou-guang; Wen, Zhan-bo; Li, Jin-song

    2015-09-01

    In this study, we evaluated the bacterial, fungal aerosol concentration, and particle size distribution using microbiological aerosol sampler, and analyzed the particles count concentration of PM1.0, PM2.5, PM5.0 and PM10.0 using aerodynamic particle sizer during clear and haze days in Beijing during Jan 8th, 2013 to Feb 4th, 2013. The concentration of bacterial, fungal aerosol, air particulate matter and aerosol distribution were compared between haze days and clear days. Our results indicated that the proportion of fungal particles smaller than 5 micron, which could deposit in lungs or deeper regions, was much higher than bacterial particles. The biological concentration of bacteria and fungi were higher in clear days than in haze days, and there was no statistic difference of the microbiological aerosol distribution. The concentration of air particulate matter were higher in haze days than in clear days, PM10 was the main particulate matters both in clear days and haze days.

  20. Air pollutant concentrations near three Texas roadways, Part I: Ultrafine particles

    Science.gov (United States)

    Zhu, Yifang; Pudota, Jayanth; Collins, Donald; Allen, David; Clements, Andrea; DenBleyker, Allison; Fraser, Matt; Jia, Yuling; McDonald-Buller, Elena; Michel, Edward

    Vehicular emitted air pollutant concentrations were studied near three types of roadways in Austin, Texas: (1) State Highway 71 (SH-71), a heavily traveled arterial highway dominated by passenger vehicles; (2) Interstate 35 (I-35), a limited access highway north of Austin in Georgetown; and (3) Farm to Market Road 973 (FM-973), a heavily traveled surface roadway dominated by truck traffic. Air pollutants examined include carbon monoxide (CO), oxides of nitrogen (NO x), and carbonyl species in the gas-phase. In the particle phase, ultrafine particle (UFP) concentrations (diameter duty traffic, wind speed, and proximity to the road were found to be the most important factors determining UFP concentrations near the roadways. Since wind directions were not consistent during the sampling periods, distances along wind trajectories from the roadway to the sampling points were used to study the decay characteristics of UFPs. Under perpendicular wind conditions, for all studied roadway types, particle number concentrations increased dramatically moving from the upwind side to the downwind side. The elevated particle number concentrations decay exponentially with increasing distances from the roadway with sharp concentration gradients observed within 100-150 m, similar to previously reported studies. A single exponential decay curve was found to fit the data collected from all three roadways very well under perpendicular wind conditions. No consistent pattern was observed for UFPs under parallel wind conditions. However, regardless of wind conditions, particle concentrations returned to background levels within a few hundred meters of the roadway. Within measured UFP size ranges, smaller particles (6-25 nm) decayed faster than larger ones (100-300 nm). Similar decay rates were observed among UFP number, surface, and volume.

  1. Magnetofluidic concentration and separation of non-magnetic particles using two magnet arrays.

    Science.gov (United States)

    Hejazian, Majid; Nguyen, Nam-Trung

    2016-07-01

    The present paper reports the use of diluted ferrofluid and two arrays of permanent magnets for the size-selective concentration of non-magnetic particles. The micro magnetofluidic device consists of a straight channels sandwiched between two arrays of permanent magnets. The permanent magnets create multiple capture zones with minimum magnetic field strength along the channel. The complex interaction between magnetic forces and hydrodynamic force allows the device to operate in different regimes suitable for concentration of non-magnetic particles with small difference in size. Our experimental results show that non-magnetic particles with diameters of 3.1 μm and 4.8 μm can be discriminated and separated with this method. The results from this study could be used as a guide for the design of size-sensitive separation devices for particle and cell based on negative magnetophoresis.

  2. EVOLUTION OF NUMBER CONCENTRATION OF NANO-PARTICLES UNDERGOING BROWNIAN COAGULATION IN THE TRANSITION REGIME

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-ming; LIN Jian-zhong

    2011-01-01

    Evolution of number concentration of nanoparticles undergoing Brownian coagulation in the transition regime is studied theoretically and numerically.The results show that the curves of particle size distribution move toward the area with large particle diameters,the curve peak becomes lower and the range that particle diameters cover becomes wider as time elapses.In the process of coagulation the particles with small diameter disappear gradually and the particle size distribution remains a log-normal distribution.The change rate of the particle size distribution is more appreciable at the initial stage than that at the final stage.The initial Knudsen number has a significant effect on the coagulation rate which increases with decreasing the initial Knudsen number.The larger the initial geometric standard deviation is,the smaller the curve peak is,and the wider the area that curves cover is.The initial geometric standard deviation has a significant effect on the particle size distribution which can remain a self-preserving state when the initial geometric standard deviation is smaller than 2.With the increase of the diversity of initial particle size,the particle size distribution does not obey the log-normal distribution any more as time elapses.

  3. Estimation of Collection Efficiency Depended on Feed Particle Concentration for Axial Flow Cyclone Dust Collector

    Institute of Scientific and Technical Information of China (English)

    AkiraOgawa

    1999-01-01

    A cyclone dust collector is applied in many industries.Especially the axial flow cyclone is the most simple construction and if keeps high reliability for maintenance.On the other hand,the collection efficiency of the cyclone depends not only on the inlet gas velocity but also on the feed particle concentration.The collection efficiency increases with increasing feed particle concentration.However until now the problem of how to estimate the collection efficiency depended on the feed particle concentration is remained except the investigation by Muschelknautz & Brunner[6],Therefore in this paper one of the estimate method for the collection efficiency of the axial flow cyclones is proposed .The application to the geometrically similar type of cyclone of the body diameters D1=30,50,69and 99mm showed in good agreement with the experimental results of the collection efficiencies which were described in detail in the paper by ogawa & Sugiyama[8].

  4. PARTICLE CONCENTRATIONS IN A CHURCH DURING DIFFERENT WEATHER CONDITIONS – A CASE STUDY

    Directory of Open Access Journals (Sweden)

    Bernard Polednik

    2016-11-01

    Full Text Available The purpose of this study is to report particle number (PN and particle mass (PM concentration changes in the church during three 60-minute Masses held on a cloudy, sunny and rainy day. At each Mass with a similar number of participants the same number of candles was lit and incense was burned. The highest average PN1 and PM1 concentrations of submicrometer particles which respectively amounted to 23.9 pt/cm3 and 241.1 µg/m3 were obtained for the Mass held on a rainy day. During that Mass the maximum PN1 and PM1 concentrations (amounting to 59.4×103 pt/cm3 and 632 µg/m3 were respectively about 15 and 39 times higher than the church background levels. The greatest number of submicrometer particles (about 18.5×109 was inhaled by an average participant of the Mass held on a sunny day and it was approximately 7 times higher than the number that would have been inhaled at the same time outdoors. The greatest mass of such particles (about 195.4 µg was inhaled by an average participant of the Mass held on a rainy day and it was approximately 8 times higher than the mass of particles that would have been inhaled outdoors during the same time.

  5. Evaluation of correlating factors between {sup 238}U concentration measured in fine and course atmospheric particles

    Energy Technology Data Exchange (ETDEWEB)

    Peixoto, Claudia Marques; Jacomino, Vanusa Maria Feliciano; Barreto, Alberto Avelar; Dias, Vagner Silva, E-mail: cmp@cdtn.b, E-mail: vmfj@cdtn.b, E-mail: aab@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Dias, Fabiana Ferrari, E-mail: fdias@cnen.gov.b [Brazilian Nuclear Energy Commission (CNEN-/MG), Pocos de Caldas, MG (Brazil). Lab. de Pocos de Caldas (LAPOC)

    2009-07-01

    Air quality is ever more important in function of the enormous proportion of human actions that have affected the environment over the last two centuries. Particulate material is one among many pollutants that can cause great risk to human health and the environment. It can be classified as: Total Suspended Particles (TSP), defined simply as particles with less than 50 mum aerodynamic diameter (one group of these particles can be inhaled and may cause health problems, while others may unfavorably affect the population's quality of life, interfering in environmental conditions and impairing normal community activities); and Inhalable Particles (PM{sub 10}), defined as those particles with less than 10 mum aerodynamic diameter. These particles penetrate the respiratory system and can reach pulmonary alveoli due to their small size, causing serious health damage. The Nuclear Technology Development Center (CDTN) has monitored air quality around its installations since 2000. CDTN's Environmental Monitoring Program (EMP) includes monitoring radioactivity levels contained in atmospheric TSP. In order to optimize its program, CDTN is carrying out a study to estimate the correlation between concentrations of particulate material measured in TSP and those measured in PM{sub 10}, PI{sub 2.5} and PI{sub 1}, as well as determination of activity concentration for each controlled radionuclide in all parts. The objective of this study is to present preliminary results and report {sup 238}U activity concentration results. (author)

  6. Biological aerosol particle concentrations and size distributions measured in pristine tropical rainforest air during AMAZE-08

    OpenAIRE

    J. A. Huffman; Sinha, B.; R. M. Garland; A. Snee-Pollmann; Gunthe, S. S.; Artaxo, P.; S. T. Martin; Andreae, M. O.; U. Pöschl

    2012-01-01

    As a part of the AMAZE-08 campaign during the wet season in the rainforest of Central Amazonia, an ultraviolet aerodynamic particle sizer (UV-APS) was operated for continuous measurements of fluorescent biological aerosol particles (FBAP). In the coarse particle size range (> 1 μm) the campaign median and quartiles of FBAP number and mass concentration were 7.3 × 104 m−3 (4.0–13.2 × 104 m&m...

  7. Exploring Soot Particle Concentration and Emissivity by Transient Thermocouples Measurements in Laminar Partially Premixed Coflow Flames

    Directory of Open Access Journals (Sweden)

    Gianluigi De Falco

    2017-02-01

    Full Text Available Soot formation in combustion represents a complex phenomenon that strongly depends on several factors such as pressure, temperature, fuel chemical composition, and the extent of premixing. The effect of partial premixing on soot formation is of relevance also for real combustion devices and still needs to be fully understood. An improved version of the thermophoretic particle densitometry (TPD method has been used in this work with the aim to obtain both quantitative and qualitative information of soot particles generated in a set of laminar partially-premixed coflow flames characterized by different equivalence ratios. To this aim, the transient thermocouple temperature response has been analyzed to infer particle concentration and emissivity. A variety of thermal emissivity values have been measured for flame-formed carbonaceous particles, ranging from 0.4 to 0.5 for the early nucleated soot particles up to the value of 0.95, representing the typical value commonly attributed to mature soot particles, indicating that the correct determination of the thermal emissivity is necessary to accurately evaluate the particle volume fraction. This is particularly true at the early stage of the soot formation, when particle concentration measurement is indeed particularly challenging as in the central region of the diffusion flames. With increasing premixing, an initial increase of particles is detected both in the maximum radial soot volume fraction region and in the central region of the flame, while the further addition of primary air determines the particle volume fraction drop. Finally, a modeling analysis based on a sectional approach has been performed to corroborate the experimental findings.

  8. Spatial & temporal variations of PM10 and particle number concentrations in urban air.

    Science.gov (United States)

    Johansson, Christer; Norman, Michael; Gidhagen, Lars

    2007-04-01

    The size of particles in urban air varies over four orders of magnitude (from 0.001 microm to 10 microm in diameter). In many cities only particle mass concentrations (PM10, i.e. particles road surface is an important factor for the highest PM10 concentrations observed. In Stockholm, road wear increases drastically due to the use of studded tires and traction sand on streets during winter; up to 90% of the locally emitted PM10 may be due to road abrasion. PM10 emissions and concentrations, but not PNC, at kerbside are controlled by road moisture. Annual mean urban background PM10 levels are relatively uniformly distributed over the city, due to the importance of long range transport. For PNC local sources often dominate the concentrations resulting in large temporal and spatial gradients in the concentrations. Despite these differences in the origin of PM10 and PNC, the spatial gradients of annual mean concentrations due to local sources are of equal magnitude due to the common source, namely traffic. Thus, people in different areas experiencing a factor of 2 different annual PM10 exposure due to local sources will also experience a factor of 2 different exposure in terms of PNC. This implies that health impact studies based solely on spatial differences in annual exposure to PM10 may not separate differences in health effects due to ultrafine and coarse particles. On the other hand, health effect assessments based on time series exposure analysis of PM10 and PNC, should be able to observe differences in health effects of ultrafine particles versus coarse particles.

  9. Urban background levels of particle number concentration and sources in Vilnius, Lithuania

    Science.gov (United States)

    Byčenkienė, Steigvilė; Plauškaitė, Kristina; Dudoitis, Vadimas; Ulevicius, Vidmantas

    2014-06-01

    This study presents results of research on urban aerosol particles with a focus on the aerosol particle number concentration (PNC) and the particle size distribution. The real time measurements of aerosol PNC (> 4.5 nm) and number size distributions (9-840 nm) were performed. The seasonal variations essentially comprised the minimum monthly mean in October 2010 (3400 ± 3000 cm- 3) and the maximum in April 2011 (19,000 ± 15,000 cm- 3). The mean annual PNC was 10,000 ± 8000 cm- 3 with an average mode size of 30-50 nm. The presence of strong diurnal patterns in aerosol PNC was evident as a direct effect of three sources of aerosol particles (nucleation, traffic, and residential heating). Hybrid receptor modeling potential source contribution function (PSCF) and concentration weighted trajectory (CWT) were used by incorporating 72-h backward trajectories and measurements of PNC in Vilnius. The results of trajectory clustering and the PSCF method demonstrated that possible additional source areas contributing to the elevated particle number concentration in Vilnius could be industrial areas in central Europe. Principal component analysis (PCA) revealed highest loadings for PNC, PM10, NOx, NO, NO2 and SO2 concentrations, indicating combustion processes occurring in vehicle engines and use of sulfur-containing fossil fuels for residential heating.

  10. Contribution of ship traffic to aerosol particle concentrations downwind of a major shipping lane

    DEFF Research Database (Denmark)

    Kivekäs, N.; Massling, Andreas; Grythe, H.

    2014-01-01

    by 790 cm(-3) by number and 0.10 gm(-3) by mass. The corresponding daily average values were 170 cm-3 and 0.023 gm-3, respectively. This means that the ship plumes contributed between 11 and 19% to the particle number concentration and between 9 and 18% to PM0.15 during days when air was arriving over......Particles in the atmosphere are of concern due to their toxic properties and effects on climate. In coastal areas, ship emissions can be a significant anthropogenic source. In this study we investigated the contribution from ship emissions to the total particle number and mass concentrations...... at a remote location. We studied the particle number concentration (12 to 490 nm in diameter), the mass concentration (12 to 150 nm in diameter) and number and volume size distribution of aerosol particles in ship plumes for a period of 4.5 months at Hovsore, a coastal site on the western coast of Jutland...

  11. Explaining global surface aerosol number concentrations in terms of primary emissions and particle formation

    Directory of Open Access Journals (Sweden)

    D. V. Spracklen

    2010-05-01

    Full Text Available We synthesised observations of total particle number (CN concentration from 36 sites around the world. We found that annual mean CN concentrations are typically 300–2000 cm−3 in the marine boundary layer and free troposphere (FT and 1000–10 000 cm−3 in the continental boundary layer (BL. Many sites exhibit pronounced seasonality with summer time concentrations a factor of 2–10 greater than wintertime concentrations. We used these CN observations to evaluate primary and secondary sources of particle number in a global aerosol microphysics model. We found that emissions of primary particles can reasonably reproduce the spatial pattern of observed CN concentration (R2=0.46 but fail to explain the observed seasonal cycle (R2=0.1. The modeled CN concentration in the FT was biased low (normalised mean bias, NMB=−88% unless a secondary source of particles was included, for example from binary homogeneous nucleation of sulfuric acid and water (NMB=−25%. Simulated CN concentrations in the continental BL were also biased low (NMB=−74% unless the number emission of anthropogenic primary particles was increased or a mechanism that results in particle formation in the BL was included. We ran a number of simulations where we included an empirical BL nucleation mechanism either using the activation-type mechanism (nucleation rate, J, proportional to gas-phase sulfuric acid concentration to the power one or kinetic-type mechanism (J proportional to sulfuric acid to the power two with a range of nucleation coefficients. We found that the seasonal CN cycle observed at continental BL sites was better simulated by BL particle formation (R2=0.3 than by increasing the number emission from primary anthropogenic sources (R2=0.18. The nucleation constants that resulted in best overall match between model and observed CN concentrations were

  12. RELATIVE LEVELS OF INDOOR AND OUTDOOR PARTICLE NUMBER CONCENTRATIONS IN A RESIDENTIAL BUILDING IN XI'AN

    Institute of Scientific and Technical Information of China (English)

    Yanming Kang; Ke Zhong; Shun-Cheng Lee

    2006-01-01

    The time series of indoor and outdoor particle number concentrations in a naturally ventilated residential building in Xi'an were tested simultaneously for 7 days in summer. The relationships between indoor and outdoor concentrations were examined and discussed, and linear regression analysis was employed to correlate the indoor and outdoor concentrations. The diurnal cycles of indoor and outdoor particle concentrations of different particle size ranges all showed positive correlations between indoor and outdoor number concentrations. The I/O ratios of number concentrations varied with the increase of particle size in the range of 0.89 (±0.19) to 0.99 (±0.15).

  13. A fiber-optic probe for particle sizing in concentrated suspensions

    Science.gov (United States)

    Dhadwal, Harbans S.; Ansari, Rafat R.; Meyer, William V.

    1991-01-01

    A fiber-optic probe employing two monomode optical fibers, one for transmitting a Gaussian laser beam to the scattering volume and the second, positioned at some backscatter angle, for receiving the scattered light is described. Performance and suitability of the system for a process control environment is assessed by studying a suspension of polystyrene latex particles over a wide range of sizes and concentrations. The results show that the probe is ideal for a process control environment in industrial and laboratory applications. Particle size is recovered, without any additional corrections for multiple light scattering, in concentrations containing up to 10 percent solids of 39-nm polystyrene latex spheres.

  14. Aerosol concentration and particle size distributions in underground excavations of a hard coal mine.

    Science.gov (United States)

    Skubacz, Krystian; Wojtecki, Łukasz; Urban, Paweł

    2017-09-01

    Deposition of aerosols in the respiratory system depends inter alia on their size and the respiratory tract deposition is appreciable for nanometer-sized particles. This article presents the results of measurements of size distributions of aerosols in the range of several nanometers up to about 20 μm in the underground mine excavations of an active hard coal mine. The study included practically all particles of a respirable fraction. The results showed that a high concentration of fine and ultrafine aerosols occurs in key underground workplaces especially during mining machine operations, although their contribution to total mass concentration is usually negligible.

  15. Preferential concentration of inertial sub-kolmogorov particles. The roles of mass loading of particles, Stokes and Reynolds numbers

    CERN Document Server

    Sumbekova, Sholpan; Aliseda, Alberto; Bourgoin, Mickael

    2016-01-01

    Turbulent flows laden with inertial particles present multiple open questions and are a subject of great interest in current research. Due to their higher density compared to the carrier fluid, inertial particles tend to form high concentration regions, i.e. clusters, and low concentration regions, i.e. voids, due to the interaction with the turbulence. In this work, we present an experimental investigation of the clustering phenomenon of heavy sub-Kolmogorov particles in homogeneous isotropic turbulent flows. Three control parameters have been varied over significant ranges: $Re_{\\lambda} \\in [170 - 450]$, $St\\in [0.1 - 5]$ and volume fraction $\\phi_v\\in [2\\times 10^{-6} - 2\\times 10^{-5}]$. The scaling of clustering characteristics, such as the distribution of Vorono\\"i areas and the dimensions of cluster and void regions, with the three parameters are discussed. In particular, for the polydispersed size distributions considered here, clustering is found to be enhanced strongly (quasi-linearly) by $Re_{\\lam...

  16. Concentrations of fine, ultrafine, and black carbon particles in auto-rickshaws in New Delhi, India

    Science.gov (United States)

    Apte, Joshua, S.; Kirchstetter, Thomas W.; Reich, Alexander, H.; Deshpande, Shyam J.; Kaushik, Geetanjali; Chel, Arvind; Marshall, Julian D.; Nazaroff, William W.

    2011-08-01

    Concentrations of air pollutants from vehicles are elevated along roadways, indicating that human exposure in transportation microenvironments may not be adequately characterized by centrally located monitors. We report results from ˜180 h of real-time measurements of fine particle and black carbon mass concentration (PM 2.5, BC) and ultrafine particle number concentration (PN) inside a common vehicle, the auto-rickshaw, in New Delhi, India. Measured exposure concentrations are much higher in this study (geometric mean for ˜60 trip-averaged concentrations: 190 μg m -3 PM 2.5, 42 μg m -3 BC, 280 × 10 3 particles cm -3; GSD ˜1.3 for all three pollutants) than reported for transportation microenvironments in other megacities. In-vehicle concentrations exceeded simultaneously measured ambient levels by 1.5× for PM 2.5, 3.6× for BC, and 8.4× for PN. Short-duration peak concentrations (averaging time: 10 s), attributable to exhaust plumes of nearby vehicles, were greater than 300 μg m -3 for PM 2.5, 85 μg m -3 for BC, and 650 × 10 3 particles cm -3 for PN. The incremental increase of within-vehicle concentration above ambient levels—which we attribute to in- and near-roadway emission sources—accounted for 30%, 68% and 86% of time-averaged in-vehicle PM 2.5, BC and PN concentrations, respectively. Based on these results, we estimate that one's exposure during a daily commute by auto-rickshaw in Delhi is as least as large as full-day exposures experienced by urban residents of many high-income countries. This study illuminates an environmental health concern that may be common in many populous, low-income cities.

  17. Biological aerosol particle concentrations and size distributions measured in pristine tropical rainforest air during AMAZE-08

    Science.gov (United States)

    Huffman, J. A.; Sinha, B.; Garland, R. M.; Snee-Pollmann, A.; Gunthe, S. S.; Artaxo, P.; Martin, S. T.; Andreae, M. O.; Pöschl, U.

    2012-09-01

    As a part of the AMAZE-08 campaign during the wet season in the rainforest of Central Amazonia, an ultraviolet aerodynamic particle sizer (UV-APS) was operated for continuous measurements of fluorescent biological aerosol particles (FBAP). In the coarse particle size range (> 1 μm) the campaign median and quartiles of FBAP number and mass concentration were 7.3 × 104 m-3 (4.0-13.2 × 104 m-3) and 0.72 μg m-3 (0.42-1.19 μg mm-3), respectively, accounting for 24% (11-41%) of total particle number and 47% (25-65%) of total particle mass. During the five-week campaign in February-March 2008 the concentration of coarse-mode Saharan dust particles was highly variable. In contrast, FBAP concentrations remained fairly constant over the course of weeks and had a consistent daily pattern, peaking several hours before sunrise, suggesting observed FBAP was dominated by nocturnal spore emission. This conclusion was supported by the consistent FBAP number size distribution peaking at 2.3 μm, also attributed to fungal spores and mixed biological particles by scanning electron microscopy (SEM), light microscopy and biochemical staining. A second primary biological aerosol particle (PBAP) mode between 0.5 and 1.0 μm was also observed by SEM, but exhibited little fluorescence and no fungal staining. This mode consisted of single bacterial cells, brochosomes and various fragments of biological material. Particles liquid-coated with mixed organic-inorganic material constituted a large fraction of observations, and these coatings contained salts likely from primary biological origin. We provide key support for the suggestion that real-time laser-induce fluorescence (LIF) techniques provide size-resolved concentrations of FBAP as a lower limit for the atmospheric abundance of biological particles. We also show that primary biological particles, fungal spores in particular, are key fractions of supermicron aerosol in the Amazon and that, especially when coated by mixed inorganic

  18. Biological aerosol particle concentrations and size distributions measured in pristine tropical rainforest air during AMAZE-08

    Directory of Open Access Journals (Sweden)

    J. A. Huffman

    2012-09-01

    Full Text Available As a part of the AMAZE-08 campaign during the wet season in the rainforest of Central Amazonia, an ultraviolet aerodynamic particle sizer (UV-APS was operated for continuous measurements of fluorescent biological aerosol particles (FBAP. In the coarse particle size range (> 1 μm the campaign median and quartiles of FBAP number and mass concentration were 7.3 × 104 m−3 (4.0–13.2 × 104 m−3 and 0.72 μg m−3 (0.42–1.19 μg mm−3, respectively, accounting for 24% (11–41% of total particle number and 47% (25–65% of total particle mass. During the five-week campaign in February–March 2008 the concentration of coarse-mode Saharan dust particles was highly variable. In contrast, FBAP concentrations remained fairly constant over the course of weeks and had a consistent daily pattern, peaking several hours before sunrise, suggesting observed FBAP was dominated by nocturnal spore emission. This conclusion was supported by the consistent FBAP number size distribution peaking at 2.3 μm, also attributed to fungal spores and mixed biological particles by scanning electron microscopy (SEM, light microscopy and biochemical staining. A second primary biological aerosol particle (PBAP mode between 0.5 and 1.0 μm was also observed by SEM, but exhibited little fluorescence and no fungal staining. This mode consisted of single bacterial cells, brochosomes and various fragments of biological material. Particles liquid-coated with mixed organic-inorganic material constituted a large fraction of observations, and these coatings contained salts likely from primary biological origin. We provide key support for the suggestion that real-time laser-induce fluorescence (LIF techniques provide size-resolved concentrations of FBAP as a lower limit for the atmospheric abundance of biological particles. We also show that primary biological particles, fungal spores in particular, are key

  19. [Study on number concentration distribution of atmospheric ultrafine particles in Hangzhou].

    Science.gov (United States)

    Xie, Xiao-Fang; Sun, Zai; Fu, Zhi-Min; Yang, Wen-Jun; Lin, Jian-Zhong

    2013-02-01

    Atmospheric ultrafine particles (UFPs) were measured with fast mobility particle sizer(FMPS) in Hangzhou, during March 2011 to February 2012. The number concentration and size distribution of UFPs associated with meteorology were studied. The results showed that the number concentration of UFPs was logarithmic bi-modal distribution, and the seasonal levels presented winter > summer > spring> autumn. The highest monthly average concentration was 3.56 x 10(4) cm-3 in December and the lowest was 2.51 x 10(4) cm-3 in October. The seasonal values of count medium diameter(CMD) were spring > winter > autumn > summer. The highest monthly average CMD was 53. 51 nm in April and the lowest was 16.68 nm in June. Meteorological factors had effects on concentration of UFPs.

  20. A Simple Parametrization for the Concentration Variance Dissipation in a Lagrangian Single-Particle Model

    Science.gov (United States)

    Ferrero, Enrico; Mortarini, Luca; Purghè, Federico

    2016-11-01

    A model for the evaluation of the concentration fluctuation variance is coupled with a one-particle Lagrangian stochastic model and results compared to a wind-tunnel simulation experiment. In this model the concentration variance evolves along the particle trajectories according to the same Langevin equation used for the simulation of the velocity field, and its dissipation is taken into account through a decay term with a finite time scale. Indeed, while the mean concentration is conserved, the concentration variance is not and our model takes into account its dissipation. A simple parametrization for the dissipation time scale is proposed and it is found that it depends linearly on time and on the ratio between the size and the height of the source through a scaling factor of 1 / 3.

  1. Characterization study of cesium concentrated particles in the soils near the Fukushima Daiichi nuclear power plant

    Science.gov (United States)

    Satou, Yukihiko; Sueki, Keisuke; Sasa, Kimikazu; Adachi, Kouji; Igarashi, Yasuhito

    2015-04-01

    Radionuclides from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident contaminated a vast area. Two types of contamination, spread and spot types, were observed in soils with autoradiography using an imaging plate. Other samples such as dust filters, vegetation, X-ray films, and so on, also indicate the spot type contamination in the early stage of the FDNPP accident. The source of spot type contamination is well known as hot particles at the Chernobyl Nuclear Power Plant (ChNPP) accident in 1986. Hot particles were divided into two groups, fuel hot particles and fission product particles, and they were emitted directly from reactor core with phreatic explosion and fire. In contrast, the official reports of the FDNPP accident did not conforme core explosion. In addition, the emitted total amount of Uranium was very few (Yamamoto et al., 2014). Thus, the spot type contaminations were not identified as the same of hot particles yet. Therefore, the present study aimed to pick up and identify the spot contaminations in soils. Surface soil samples were collected at 20 km northwest from the FDNPP in June 2013. Soils were spread in plastic bags for autoradiography with imaging plate analysis. Then, the soil particles were collected on a sticky carbon tape and analyzed by SEM-EDS to detect radioactive particles. Finally, particles were confirmed to contain photo peaks in the γ-spectrum by a germanium semiconductor detector. Four radioactive particles were isolated from the soil samples in the present study. Detected γ-ray emission radionuclides were only Cs-134 and Cs-137. The X-ray spectra on the SEM-EDS of all particles showed a Cs peak as well as O, Fe, Zn, and Rb peaks, and these elements were distributed uniformly within the particles. In addition, uniform distribution of Si was also shown. Moreover, U was detected from one of the particles, but U concentration was very low and existed locally in the particle. These characters are very similar to previous

  2. Assessment of exposure to respirable particles (PM2.5 concentrations in public transportation

    Directory of Open Access Journals (Sweden)

    M. Mohammadian

    2006-01-01

    Full Text Available Background and purpose: High concentrations of respirable particles may cause high incidence of respiratory diseases and mortality. Epidemiological exposure assessment is based on fixed site measurements in ambient air. However, major studies reported good relationship between indoor fine particulate air concentrations and personal exposure. This study is focussed on personal exposure to PM2.5 in different transportation modes and factors that cause high indoor PM2.5 levels.Materials and Methods: In this study, a calibrated real time monitor (MicroDust Pro was used to measure PM2.5 levels in 3 mode of transportation (bus, car and train on the same route. Results were also compared with PM10 concentrations measured by fixed site monitors. A small Poly Urethane Foam (PFU filter was designed for PM2.5 size fraction monitoring and a small personal sampling pump was used to provide a continuous airflow through the gravimetric adaptor and photo detector.Results: The mean PM2.5 concentration measured in the train was lower than the mean fixed site PM10 concentration. However, the mean PM2.5 levels in car and bus were much higher than those mean PM10 concentrations measured by fixed site monitors. Boarding, picking up, dropping off, and movement of passengers inside the bus and train were significantly related to short-term increases in PM2.5 concentrations. However, stopping at the traffic light was the most important factor associated with peak PM2.5 concentrations inside the car.Conclusion: Penetration of particles that were created by road traffic and resuspension of fine particles in the vehicles were the most important factors that may increase respirable particles in transportation modes.

  3. Volatile Release and Ignition Behaviors of Single Coal Particles at Different Oxygen Concentrations Under Microgravity

    Science.gov (United States)

    Liu, Bing; Zhang, Zhezi; Zhang, Hai; Zhang, Dongke

    2016-05-01

    An experimental study on ignition and combustion of single coal particles under different O 2 concentrations was conducted at both normal (1-g) and microgravity ( μ-g) in the first time. The surface and centre temperatures of the bituminous coal particle with initial diameter of ˜ 2.0mm were measured by the monochromatic imaging technique using a short wavelength infrared (SWIR) camera and an embedded fine thermocouple respectively. Results revealed that at μ-g, ignition of the tested coal particles was homogeneous. O 2 concentration significantly affects the shape, ignition temperature and ignition delay time of the volatile flames. A mathematical model considering thermal conduction inside the coal particle was developed to describe the ignition process of single particle, adopting the volatile matter flammability limit as the homogeneous ignition criterion. The predicted ignition temperatures were slightly lower but closer to μ-g data. And the predicted variation trends of ignition temperature and delay time under different O 2 concentrations agreed well with the μ-g experimental results.

  4. Development of a Magnetic Resonance Imaging-Based Method for Particle Concentration Measurement

    Science.gov (United States)

    Borup, Daniel D.; Elkins, Christopher J.; Eaton, John K.

    2016-11-01

    Magnetic Resonance Imaging (MRI) is well suited for the study of fluid mechanics in complex flows where optical access is not possible. Current MRI-based techniques allow for the measurement of 3D, 3-component velocity and scalar concentration fields. The current work aims to develop and validate a technique for measuring the concentration of a dispersed phase of solid microspheres in a turbulent water flow. Such a diagnostic would allow for the study of the transport of small particles in arbitrarily complicated biological, engineering, or natural flows. In the presence of paramagnetic particles, MRI signal decays more rapidly than it does for pure water due to small disturbances in the magnetic field. We predicted the spatial extent and magnitude of this disturbance using a standard theoretical framework for MRI and obtained reasonable agreement with experimental results. Using the linear relationship between particle volume fraction and signal decay rate, we also obtained 3D concentration data for a particle streak injected into a ribbed serpentine channel flow. These data were used to validate the new method, and the transport of solid particles was compared to the transport of a passive scalar in the same flow. Daniel Borup is supported by NSF Grant No. DGE-114747.

  5. Ratios of total suspended solids to suspended sediment concentrations by particle size

    Science.gov (United States)

    Selbig, W.R.; Bannerman, R.T.

    2011-01-01

    Wet-sieving sand-sized particles from a whole storm-water sample before splitting the sample into laboratory-prepared containers can reduce bias and improve the precision of suspended-sediment concentrations (SSC). Wet-sieving, however, may alter concentrations of total suspended solids (TSS) because the analytical method used to determine TSS may not have included the sediment retained on the sieves. Measuring TSS is still commonly used by environmental managers as a regulatory metric for solids in storm water. For this reason, a new method of correlating concentrations of TSS and SSC by particle size was used to develop a series of correction factors for SSC as a means to estimate TSS. In general, differences between TSS and SSC increased with greater particle size and higher sand content. Median correction factors to SSC ranged from 0.29 for particles larger than 500m to 0.85 for particles measuring from 32 to 63m. Great variability was observed in each fraction-a result of varying amounts of organic matter in the samples. Wide variability in organic content could reduce the transferability of the correction factors. ?? 2011 American Society of Civil Engineers.

  6. Concentrations and Sources of Airborne Particles in a Neonatal Intensive Care Unit

    Science.gov (United States)

    Licina, Dusan; Bhangar, Seema; Brooks, Brandon; Baker, Robyn; Firek, Brian; Tang, Xiaochen; Morowitz, Michael J.; Banfield, Jillian F.; Nazaroff, William W.

    2016-01-01

    Premature infants in neonatal intensive care units (NICUs) have underdeveloped immune systems, making them susceptible to adverse health consequences from air pollutant exposure. Little is known about the sources of indoor airborne particles that contribute to the exposure of premature infants in the NICU environment. In this study, we monitored the spatial and temporal variations of airborne particulate matter concentrations along with other indoor environmental parameters and human occupancy. The experiments were conducted over one year in a private-style NICU. The NICU was served by a central heating, ventilation and air-conditioning (HVAC) system equipped with an economizer and a high-efficiency particle filtration system. The following parameters were measured continuously during weekdays with 1-min resolution: particles larger than 0.3 μm resolved into 6 size groups, CO2 level, dry-bulb temperature and relative humidity, and presence or absence of occupants. Altogether, over sixteen periods of a few weeks each, measurements were conducted in rooms occupied with premature infants. In parallel, a second monitoring station was operated in a nearby hallway or at the local nurses’ station. The monitoring data suggest a strong link between indoor particle concentrations and human occupancy. Detected particle peaks from occupancy were clearly discernible among larger particles and imperceptible for submicron (0.3–1 μm) particles. The mean indoor particle mass concentrations averaged across the size range 0.3–10 μm during occupied periods was 1.9 μg/m3, approximately 2.5 times the concentration during unoccupied periods (0.8 μg/m3). Contributions of within-room emissions to total PM10 mass in the baby rooms averaged 37–81%. Near-room indoor emissions and outdoor sources contributed 18–59% and 1–5%, respectively. Airborne particle levels in the size range 1–10 μm showed strong dependence on human activities, indicating the importance of indoor

  7. Concentrations and Sources of Airborne Particles in a Neonatal Intensive Care Unit.

    Directory of Open Access Journals (Sweden)

    Dusan Licina

    Full Text Available Premature infants in neonatal intensive care units (NICUs have underdeveloped immune systems, making them susceptible to adverse health consequences from air pollutant exposure. Little is known about the sources of indoor airborne particles that contribute to the exposure of premature infants in the NICU environment. In this study, we monitored the spatial and temporal variations of airborne particulate matter concentrations along with other indoor environmental parameters and human occupancy. The experiments were conducted over one year in a private-style NICU. The NICU was served by a central heating, ventilation and air-conditioning (HVAC system equipped with an economizer and a high-efficiency particle filtration system. The following parameters were measured continuously during weekdays with 1-min resolution: particles larger than 0.3 μm resolved into 6 size groups, CO2 level, dry-bulb temperature and relative humidity, and presence or absence of occupants. Altogether, over sixteen periods of a few weeks each, measurements were conducted in rooms occupied with premature infants. In parallel, a second monitoring station was operated in a nearby hallway or at the local nurses' station. The monitoring data suggest a strong link between indoor particle concentrations and human occupancy. Detected particle peaks from occupancy were clearly discernible among larger particles and imperceptible for submicron (0.3-1 μm particles. The mean indoor particle mass concentrations averaged across the size range 0.3-10 μm during occupied periods was 1.9 μg/m3, approximately 2.5 times the concentration during unoccupied periods (0.8 μg/m3. Contributions of within-room emissions to total PM10 mass in the baby rooms averaged 37-81%. Near-room indoor emissions and outdoor sources contributed 18-59% and 1-5%, respectively. Airborne particle levels in the size range 1-10 μm showed strong dependence on human activities, indicating the importance of indoor

  8. The Effect of Particle Concentration on the Heating Rate of Ferrofluids for Magnetic Hyperthermia

    Directory of Open Access Journals (Sweden)

    Malaescu I.

    2015-12-01

    Full Text Available The complex magnetic susceptibility χ(f = χ′(f - i χ″(f, of a ferrofluid sample with magnetite particles dispersed in kerosene and stabilized with oleic acid, over the range 0.1 GHz to 6 GHz, was determined. The initial sample has been successively diluted with kerosene (with a dilution rate of 2/3, thus obtaining further three samples. Using the complex magnetic susceptibility measurements of each sample, the frequency field and particle concentration dependencies of the heating rate of the ferrofluid samples, were analyzed. The results show the possibility of using the heating rate of ferrofluid samples with different particle concentrations, in hyperthermia applications.

  9. A Cascade Model for Particle Concentration and Enstrophy in Fully Developed Turbulence with Mass Loading Feedback

    CERN Document Server

    Hogan, Robert C

    2007-01-01

    A cascade model is described based on multiplier distributions determined from 3D direct numerical simulations (DNS) of turbulent particle laden flows, which include two-way coupling between the phases at global mass loadings equal to unity. The governing Eulerian equations are solved using pseudo-spectral methods on up to 512**3 computional grid points. DNS results for particle concentration and enstrophy at Taylor microscale Reynolds numbers in the range 34 - 170 were used to directly determine multiplier distributions (PDFs) on spatial scales 3 times the Kolmogorov length scale. The width of the PDFs, which is a measure of intermittency, decreases with increasing mass loading within the local region where the multipliers are measured. The functional form of this dependence is not sensitive to Reynolds numbers in the range considered. A partition correlation probability is included in the cascade model to account for the observed spatial anticorrelation between particle concentration and enstrophy. Joint pr...

  10. Very-Low-Density Lipoprotein (VLDL)-Producing and Hepatitis C Virus-Replicating HepG2 Cells Secrete No More Lipoviroparticles than VLDL-Deficient Huh7.5 Cells

    Science.gov (United States)

    Jammart, Baptiste; Michelet, Maud; Pécheur, Eve-Isabelle; Parent, Romain; Bartosch, Birke; Zoulim, Fabien

    2013-01-01

    In the plasma samples of hepatitis C virus (HCV)-infected patients, lipoviroparticles (LVPs), defined as (very-) low-density viral particles immunoprecipitated with anti-β-lipoproteins antibodies are observed. This HCV-lipoprotein association has major implications with respect to our understanding of HCV assembly, secretion, and entry. However, cell culture-grown HCV (HCVcc) virions produced in Huh7 cells, which are deficient for very-low-density lipoprotein (VLDL) secretion, are only associated with and dependent on apolipoprotein E (apoE), not apolipoprotein B (apoB), for assembly and infectivity. In contrast to Huh7, HepG2 cells can be stimulated to produce VLDL by both oleic acid treatment and inhibition of the MEK/extracellular signal-regulated kinase (ERK) pathway but are not permissive for persistent HCV replication. Here, we developed a new HCV cell culture model to study the interaction between HCV and lipoproteins, based on engineered HepG2 cells stably replicating a blasticidin-tagged HCV JFH1 strain (JB). Control Huh7.5-JB as well as HepG2-JB cell lines persistently replicated viral RNA and expressed viral proteins with a subcellular colocalization of double-stranded RNA (dsRNA), core, gpE2, and NS5A compatible with virion assembly. The intracellular RNA replication level was increased in HepG2-JB cells upon dimethyl sulfoxide (DMSO) treatment, MEK/ERK inhibition, and NS5A overexpression to a level similar to that observed in Huh7.5-JB cells. Both cell culture systems produced infectious virions, which were surprisingly biophysically and biochemically similar. They floated at similar densities on gradients, contained mainly apoE but not apoB, and were not neutralized by anti-apoB antibodies. This suggests that there is no correlation between the ability of cells to simultaneously replicate HCV as well as secrete VLDL and their capacity to produce LVPs. PMID:23427158

  11. Particle size distribution and PAH concentrations of incense smoke in a combustion chamber.

    Science.gov (United States)

    Yang, Chi-Ru; Lin, Ta-Chang; Chang, Feng-Hsiang

    2007-01-01

    The particle size distribution and the concentrations of polycyclic aromatic hydrocarbons (PAHs) in incense smoke were studied using a custom-designed combustion chamber. Among the nine types of incense investigated, the particle and the total PAH emission factors varied significantly. The average mass median aerodynamic diameter (MMAD) of the smoke aerosol was 262+/-49nm, which positively correlated to particle emission factor (mg/stick, pincense smoke may pose potential health risk. Experiments show that each lowered percentage of total carbon content in the raw incense helped decrease the particle emission factor by 2.6mg/g-incense, and the reduction of S-PAH emission factor ranged from 8.7 to 26% when the carbon content was lowered from 45 to 40%.

  12. Apparatus and method for concentrating and filtering particles suspended in a fluid

    Science.gov (United States)

    Fiechtner, Gregory J [Bethesda, MD; Cummings, Eric B [Livermore, CA; Singh, Anup K [Danville, CA

    2009-05-19

    Disclosed is a device for separating and concentrating particles suspended in a fluid stream by using dielectrophoresis (DEP) to trap and/or deflect those particles as they migrate through a fluid channel. The method uses fluid channels designed to constrain a liquid flowing through it to uniform electrokinetic flow velocities. This behavior is achieved by connecting deep and shallow sections of channels, with the channel depth varying abruptly along an interface. By careful design of abrupt changes in specific permeability at the interface, an abrupt and spatially uniform change in electrokinetic force can be selected. Because these abrupt interfaces also cause a sharp gradient in applied electric fields, a DEP force also can be established along the interface. Depending on the complex conductivity of the suspended particles and the immersion liquid, the DEP force can controllably complement or oppose the local electrokinetic force transporting the fluid through the channel allowing for manipulation of particles suspended in the transporting liquid.

  13. TISSUE REMODELING IN THE HUMAN LUNG IN RELATION TO PARTICLE CONCENTRATION AND METAL CONTENT

    Science.gov (United States)

    TISSUE REMODELING IN THE HUMAN LUNG IN RELATION TO PARTICLE CONCENTRATION AND METAL CONTENT. J Gallagher1, J Inmon1, S Schlaegle2, A Levine2, T Rogers3, J Scott1, F Green4, M Schenker5, K Pinkerton5 1NHEERL, US-EPA, RTP, NC, USA; 2RJ Lee Group Inc, Monroeville, Pa, USA; ...

  14. Low-Frequency Dielectric Dispersion of Highly Concentrated Spherical Particles in an Electrolyte Solution

    Institute of Scientific and Technical Information of China (English)

    倪福生; 顾国庆; 陈康民

    2002-01-01

    We deal with the problem of calculating the effective dielectric dispersion and electrical conductivity of colloidaldispersions. A comparison of the theoretical calculation of first principles with the experimental data of Schwanshows that our technique proposed here is no longer restricted to dilute solutions and is very effective for studyingthe dielectric properties of colloids with highly concentrated charged spherical particles in an electrolyte solution.

  15. Probabilistic Preparation of N-particle Cat States via Entanglement Swapping and Entanglement Concentration

    Institute of Scientific and Technical Information of China (English)

    姚春梅; 李敏; 叶柳; 郭光灿

    2002-01-01

    We discuss two different schemes for the probabilistic preparation of N-particle cat states using pure multiparticle entangled states via entanglement swapping and entanglement concentration. At the centre of distribution A,Alice performs all of the operations required to achieve our goal.

  16. Cascade model for particle concentration and enstrophy in fully developed turbulence with mass-loading feedback.

    Science.gov (United States)

    Hogan, R C; Cuzzi, J N

    2007-05-01

    A cascade model is described based on multiplier distributions determined from three-dimensional (3D) direct numerical simulations (DNS) of turbulent particle laden flows, which include two-way coupling between the phases at global mass loadings equal to unity. The governing Eulerian equations are solved using psuedospectral methods on up to 512(3) computional grid points. DNS results for particle concentration and enstrophy at Taylor microscale Reynolds numbers in the range 34-170 were used to directly determine multiplier distributions on spatial scales three times the Kolmogorov length scale. The multiplier probability distribution functions (PDFs) are well characterized by the beta distribution function. The width of the PDFs, which is a measure of intermittency, decreases with increasing mass loading within the local region where the multipliers are measured. The functional form of this dependence is not sensitive to Reynolds numbers in the range considered. A partition correlation probability is included in the cascade model to account for the observed spatial anticorrelation between particle concentration and enstrophy. Joint probability distribution functions of concentration and enstrophy generated using the cascade model are shown to be in excellent agreement with those derived directly from our 3D simulations. Probabilities predicted by the cascade model are presented at Reynolds numbers well beyond what is achievable by direct simulation. These results clearly indicate that particle mass loading significantly reduces the probabilities of high particle concentration and enstrophy relative to those resulting from unloaded runs. Particle mass density appears to reach a limit at around 100 times the gas density. This approach has promise for significant computational savings in certain applications.

  17. Primary versus secondary contributions to particle number concentrations in the European boundary layer

    Directory of Open Access Journals (Sweden)

    C. L. Reddington

    2011-06-01

    Full Text Available It is important to understand the relative contribution of primary and secondary particles to regional and global aerosol so that models can attribute aerosol radiative forcing to different sources. In large-scale models, there is considerable uncertainty associated with treatments of particle formation (nucleation in the boundary layer (BL and in the size distribution of emitted primary particles, leading to uncertainties in predicted cloud condensation nuclei (CCN concentrations. Here we quantify how primary particle emissions and secondary particle formation influence size-resolved particle number concentrations in the BL using a global aerosol microphysics model and observations made during the May 2008 campaign of the European Integrated Project on Aerosol Cloud Climate Air Quality Interactions (EUCAARI. Observations are available from the DLR Falcon 20 aircraft and from 15 ground sites of the European Supersites for Atmospheric Aerosol Research (EUSAAR and the German Ultrafine Aerosol Network (GUAN. Measurements include total and non-volatile particle number concentrations and the particle size distribution between ~3 nm and ~1 μm. We tested four different parameterisations for BL nucleation and two assumptions for the emission size distribution of anthropogenic and wildfire carbonaceous particles. When we emit small carbonaceous particles (recommended by the Aerosol Intercomparison project, AEROCOM, the spatial distributions of campaign-mean number concentrations >50 nm (N50 and >100 nm (N100 dry diameter were well captured by the model (R2~0.9 and the normalised mean bias (NMB was also small (−5 % for N50 and 12 % for N100. Emission of larger particles, which we consider to be more realistic for global models, results in equally good correlation but larger bias (R2~0.8, NMB = −51 % and −21 %, which could be partly but not

  18. Mathematical modeling of atmospheric fine particle-associated primary organic compound concentrations

    Science.gov (United States)

    Rogge, Wolfgang F.; Hildemann, Lynn M.; Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.

    1996-08-01

    An atmospheric transport model has been used to explore the relationship between source emissions and ambient air quality for individual particle phase organic compounds present in primary aerosol source emissions. An inventory of fine particulate organic compound emissions was assembled for the Los Angeles area in the year 1982. Sources characterized included noncatalyst- and catalyst-equipped autos, diesel trucks, paved road dust, tire wear, brake lining dust, meat cooking operations, industrial oil-fired boilers, roofing tar pots, natural gas combustion in residential homes, cigarette smoke, fireplaces burning oak and pine wood, and plant leaf abrasion products. These primary fine particle source emissions were supplied to a computer-based model that simulates atmospheric transport, dispersion, and dry deposition based on the time series of hourly wind observations and mixing depths. Monthly average fine particle organic compound concentrations that would prevail if the primary organic aerosol were transported without chemical reaction were computed for more than 100 organic compounds within an 80 km × 80 km modeling area centered over Los Angeles. The monthly average compound concentrations predicted by the transport model were compared to atmospheric measurements made at monitoring sites within the study area during 1982. The predicted seasonal variation and absolute values of the concentrations of the more stable compounds are found to be in reasonable agreement with the ambient observations. While model predictions for the higher molecular weight polycyclic aromatic hydrocarbons (PAH) are in agreement with ambient observations, lower molecular weight PAH show much higher predicted than measured atmospheric concentrations in the particle phase, indicating atmospheric decay by chemical reactions or evaporation from the particle phase. The atmospheric concentrations of dicarboxylic acids and aromatic polycarboxylic acids greatly exceed the contributions that

  19. Jamming, Self-Filtration and Cake Growth in Concentrated Particle Suspensions

    Science.gov (United States)

    Guo, Youjing; Li, Shoubo; Yang, Donglei; Mi, Yongli; Wang, Xiaorong

    2015-03-01

    We study the flows of concentrated particle suspensions driven through a circular orifice. Above a critical concentration, a jammed structure (i.e., quasi-solid sphere) often forms in the flow and at the entrance of the geometrical constriction. Once occurred this jammed structure grows fast as time t passes and produces a reduction in the solid concentration downstream. Our analysis shows that a combination of the particle jamming, the self-filtration, and the cake-formation with the flow passing through the pores of the jammed solid is responsible for the occurrence of such phenomena. Based on this mechanism, we establish a mathematical model to show how the jammed structure is propagated. Our results suggest that the size D of the jammed structure in this case is proportional to a 1/3 power of the time t. Experiments also support this conclusion.

  20. Power law relation between particle concentrations and their sizes in the blood plasma

    Science.gov (United States)

    Kirichenko, M. N.; Chaikov, L. L.; Zaritskii, A. R.

    2016-08-01

    This work is devoted to the investigation of sizes and concentrations of particles in blood plasma by dynamic light scattering (DLS). Blood plasma contains many different proteins and their aggregates, microparticles and vesicles. Their sizes, concentrations and shapes can give information about donor's health. Our DLS study of blood plasma reveals unexpected dependence: with increasing of the particle sizes r (from 1 nm up to 1 μm), their concentrations decrease as r-4 (almost by 12 orders). We found also that such dependence was repeated for model solution of fibrinogen and thrombin with power coefficient is -3,6. We believe that this relation is a fundamental law of nature that shows interaction of proteins (and other substances) in biological liquids.

  1. Temperature-dependent accumulation mode particle and cloud nuclei concentrations from biogenic sources during WACS 2010

    Directory of Open Access Journals (Sweden)

    L. Ahlm

    2012-10-01

    Full Text Available Submicron aerosol particles collected simultaneously at the mountain peak (2182 m a.s.l. and at a forested mid-mountain site (1300 m a.s.l. on Whistler Mountain, British Columbia, Canada, during June and July 2010 were analyzed by Fourier transform infrared (FTIR spectroscopy for quantification of organic functional groups. Positive matrix factorization (PMF was applied to the FTIR spectra. Three PMF factors associated with (1 combustion, (2 biogenics, and (3 vegetative detritus, were identified at both sites. The biogenic factor was correlated with both temperature and several volatile organic compounds (VOCs. The combustion factor dominated the submicron particle mass during the beginning of the campaign when the temperature was lower and advection was from the Vancouver area, but as the temperature started to rise in early July the biogenic factor came to dominate as a result of increased emissions of biogenic VOCs and thereby increased formation of secondary organic aerosol (SOA. On average, the biogenic factor represented 69% and 49% of the submicron organic particle mass at Whistler Peak and at the mid-mountain site, respectively. The lower fraction at the mid-mountain site was a result of more vegetative detritus there, and also higher influence from local combustion sources.

    The biogenic factor was strongly correlated (r ~ 0.9 to number concentration of particles with diameter (Dp> 100 nm, whereas the combustion factor was better correlated to number concentration of particles with Dp < 100 nm (r~ 0.4. The number concentration of cloud condensation nuclei (CCN was correlated (r ~ 0.7 to the biogenic factor for supersaturations (S of 0.2% or higher, which indicates that particle condensational growth from biogenic vapors was an important factor in controlling the CCN concentration for clouds where S≥0.2%. Both the number concentration of particles with

  2. Temperature-dependent accumulation mode particle and cloud nuclei concentrations from biogenic sources during WACS 2010

    Directory of Open Access Journals (Sweden)

    L. Ahlm

    2013-03-01

    Full Text Available Submicron aerosol particles collected simultaneously at the mountain peak (2182 m a.s.l. and at a forested mid-mountain site (1300 m a.s.l. on Whistler Mountain, British Columbia, Canada, during June and July 2010 were analyzed by Fourier transform infrared (FTIR spectroscopy for quantification of organic functional groups. Positive matrix factorization (PMF was applied to the FTIR spectra. Three PMF factors associated with (1 combustion, (2 biogenics, and (3 vegetative detritus were identified at both sites. The biogenic factor was correlated with both temperature and several volatile organic compounds (VOCs. The combustion factor dominated the submicron particle mass during the beginning of the campaign, when the temperature was lower and advection was from the Vancouver area, but as the temperature started to rise in early July, the biogenic factor came to dominate as a result of increased emissions of biogenic VOCs, and thereby increased formation of secondary organic aerosol (SOA. On average, the biogenic factor represented 69% and 49% of the submicron organic particle mass at Whistler Peak and at the mid-mountain site, respectively. The lower fraction at the mid-mountain site was a result of more vegetative detritus there, and also higher influence from local combustion sources. The biogenic factor was strongly correlated (r~0.9 to number concentration of particles with diameter (Dp> 100 nm, whereas the combustion factor was better correlated to number concentration of particles with Dpr~0.4. The number concentration of cloud condensation nuclei (CCN was correlated (r~0.7 to the biogenic factor for supersaturations (S of 0.2% or higher, which indicates that particle condensational growth from biogenic vapors was an important factor in controlling the CCN concentration for clouds where S≥0.2%. Both the number concentration of particles with Dp>100 nm and numbers of CCN for S≥0.2% were correlated to temperature. Considering the biogenic

  3. Postprandial apoE isoform and conformational changes associated with VLDL lipolysis products modulate monocyte inflammation.

    Directory of Open Access Journals (Sweden)

    Laura J den Hartigh

    Full Text Available Postprandial hyperlipemia, characterized by increased circulating very low-density lipoproteins (VLDL and circulating lipopolysaccharide (LPS, has been proposed as a mechanism of vascular injury. Our goal was to examine the interactions between postprandial lipoproteins, LPS, and apoE3 and apoE4 on monocyte activation.We showed that apoE3 complexed to phospholipid vesicles attenuates LPS-induced THP-1 monocyte cytokine expression, while apoE4 increases expression. ELISA revealed that apoE3 binds to LPS with higher affinity than apoE4. Electron paramagnetic resonance (EPR spectroscopy of site-directed spin labels placed on specific amino acids of apoE3 showed that LPS interferes with conformational changes normally associated with lipid binding. Specifically, compared to apoE4, apoE bearing the E3-like R112→Ser mutation displays increased self association when exposed to LPS, consistent with a stronger apoE3-LPS interaction. Additionally, lipolysis of fasting VLDL from normal human donors attenuated LPS-induced TNFα secretion from monocytes to a greater extent than postprandial VLDL, an effect partially reversed by blocking apoE. This effect was reproduced using fasting VLDL lipolysis products from e3/e3 donors, but not from e4/e4 subjects, suggesting that apoE3 on fasting VLDL prevents LPS-induced inflammation more readily than apoE4.Postprandial apoE isoform and conformational changes associated with VLDL dramatically modulate vascular inflammation.

  4. Influence of particles shape on the vertical profile of blowing snow concentration

    Science.gov (United States)

    Vionnet, Vincent; Trouvilliez, Alexandre; Naaim-Bouvet, Florence; Guyomarc'h, Gilbert

    2013-04-01

    In alpine regions, blowing snow events strongly influence the temporal and spatial evolution of the snow cover throughout the winter season. In Antarctica, blowing snow is an essential surface mass balance process and plays a non-negligible role in the annual accumulation. The vertical profile of blowing snow concentration determines the quantity of snow transported in turbulent suspension. A power law is often used to represent this vertical profile. It serves as an analytical solution representing an equilibrium between vertical turbulent diffusion and gravitational settling. In this work, we study how the exponent of the power law depends on the type of transported particles. Vertical profiles of blowing snow concentration have been collected at the experimental site of Col du Lac Blanc (French Alps) in 2011 and 2012 and near the research station of Cap Prud'homme (Antarctica) in 2010 and 2011. We used mechanical gauges (butterfly nets) and optical devices (Snow Particles Counters). Profiles collected during blowing snow events with precipitation have been corrected to account for the contribution of snowfall. Results show that profiles collected during blowing snow without snowfall differ from the corrected profiles collected during snowfall. At a given wind speed, particles transported during snowfall have a lower settling velocity than particles transported without snowfall. This difference confirms earlier observations (Takahashi, 1985) and can be explained by the change of drag coefficient between dendritic and rounded particles. This difference pertains several hours after the end of the snowfall illustrating the fragmentation of snow grains during blowing snow events.

  5. Thermodynamic correction of particle concentrations measured by underwing probes on fast-flying aircraft

    Science.gov (United States)

    Weigel, Ralf; Spichtinger, Peter; Mahnke, Christoph; Klingebiel, Marcus; Afchine, Armin; Petzold, Andreas; Krämer, Martina; Costa, Anja; Molleker, Sergej; Reutter, Philipp; Szakáll, Miklós; Port, Max; Grulich, Lucas; Jurkat, Tina; Minikin, Andreas; Borrmann, Stephan

    2016-10-01

    Particle concentration measurements with underwing probes on aircraft are impacted by air compression upstream of the instrument body as a function of flight velocity. In particular, for fast-flying aircraft the necessity arises to account for compression of the air sample volume. Hence, a correction procedure is needed to invert measured particle number concentrations to ambient conditions that is commonly applicable to different instruments to gain comparable results. In the compression region where the detection of particles occurs (i.e. under factual measurement conditions), pressure and temperature of the air sample are increased compared to ambient (undisturbed) conditions in certain distance away from the aircraft. Conventional procedures for scaling the measured number densities to ambient conditions presume that the air volume probed per time interval is determined by the aircraft speed (true air speed, TAS). However, particle imaging instruments equipped with pitot tubes measuring the probe air speed (PAS) of each underwing probe reveal PAS values systematically below those of the TAS. We conclude that the deviation between PAS and TAS is mainly caused by the compression of the probed air sample. From measurements during two missions in 2014 with the German Gulfstream G-550 (HALO - High Altitude LOng range) research aircraft we develop a procedure to correct the measured particle concentration to ambient conditions using a thermodynamic approach. With the provided equation, the corresponding concentration correction factor ξ is applicable to the high-frequency measurements of the underwing probes, each of which is equipped with its own air speed sensor (e.g. a pitot tube). ξ values of 1 to 0.85 are calculated for air speeds (i.e. TAS) between 60 and 250 m s-1. For different instruments at individual wing position the calculated ξ values exhibit strong consistency, which allows for a parameterisation of ξ as a function of TAS for the current HALO

  6. On the potential contribution of open lead particle emissions to the central Arctic aerosol concentration

    Directory of Open Access Journals (Sweden)

    A. Held

    2010-10-01

    Full Text Available During the ice-breaker borne ASCOS expedition (Arctic Summer Cloud Ocean Study direct eddy covariance measurements of aerosol number fluxes were carried out in August 2008 on the edge of an ice floe drifting in the central Arctic Ocean between 2°–10° W longitude and 87°–87.5° N latitude. The median aerosol transfer velocities over different surface types (open water leads, ice ridges, snow and ice surfaces ranged from 0.27 to 0.68 mm s−1 during deposition-dominated episodes. Emission periods were observed more frequently over the open lead, while the snow behaved primarily as a deposition surface. Directly measured aerosol fluxes were compared with particle deposition parameterizations in order to estimate the emission flux from the observed net aerosol flux. Finally, the contribution of the open lead particle source to atmospheric variations in particle number concentration was evaluated and compared with the observed temporal evolution of particle number. The direct emission of aerosol particles from the open lead can only explain 5–10% of the observed particle number variation in the mixing layer close to the surface.

  7. Motion and orientation of cylindrical and cubic particles in pipe flow with high concentration and high particle to pipe size ratio

    Institute of Scientific and Technical Information of China (English)

    Xiao-ke KU; Jian-zhong LIN

    2008-01-01

    Lattice Boltzmann method was used to numerically investigate the motion and orientation distribution of cylindrical and cubic particles in pipe flow with high concentration and high particle to pipe size ratio. The transient impulse model of 3D collisions between particles and between particle and wall is proposed. The numerical results are qualitatively in agreement with and quantitatively comparable to the experiment data. The results show that the increases of both the cylindrical particle to pipe size ratio and the particle aspect ratio decrease the rotation about all axes. All rotations of cubic particles decrease with increasing the particle concentration. The cubic particles, rotating more drastically in the flow with large Reynolds number, rotate faster than the cylindrical particles with the same size. The cylindrical particles align with the flow direction more obviously with decreasing Reynolds numbers. However, the orientations of cubic particles are spread all over the range with no significant difference in magnitude, and the Reynolds numbers have no obvious effect on the orientations of cubic particles.

  8. Indoor and outdoor concentrations of fine particles, particle-bound PAHs and volatile organic compounds in Kaunas, Lithuania.

    Science.gov (United States)

    Kliucininkas, Linas; Martuzevicius, Dainius; Krugly, Edvinas; Prasauskas, Tadas; Kauneliene, Violeta; Molnar, Peter; Strandberg, Bo

    2011-01-01

    This complex study presents indoor and outdoor levels of air-borne fine particles, particle-bound PAHs and VOCs at two urban locations in the city of Kaunas, Lithuania, and considers possible sources of pollution. Two sampling campaigns were performed in January-February and March-April 2009. The mean outdoor PM(2.5) concentration at Location 1 in winter was 34.5 ± 15.2 µg m(-3) while in spring it was 24.7 ± 12.2 µg m(-3); at Location 2 the corresponding values were 36.7 ± 21.7 and 22.4 ± 19.4 µg m(-3), respectively. In general there was little difference between the PM concentrations at Locations 1 and 2. PM(2.5) concentrations were lower during the spring sampling campaign. These PM concentrations were similar to those in many other European cities; however, the levels of most PAHs analysed were notably higher. The mean sum PAH concentrations at Locations 1 and 2 in the winter campaign were 75.1 ± 32.7 and 32.7 ± 11.8 ng m(-3), respectively. These differences are greater than expected from the difference in traffic intensity at the two sites, suggesting that there is another significant source of PAH emissions at Location 1 in addition to the traffic. The low observed indoor/outdoor (I/O) ratios indicate that PAH emissions at the locations studied arise primarily from outdoor sources. The buildings at both locations have old windows with wooden frames that are fairly permissive in terms of air circulation. VOC concentrations were mostly low and comparable to those reported from Sweden. The mean outdoor concentrations of VOC's were: 0.7 ± 0.2, 3.0 ± 0.8, 0.5 ± 0.2, 3.5 ± 0.3, and 0.2 ± 0.1 µg m(-3), for benzene, toluene, ethylbenzene, sum of m-, p-, o-xylenes, and naphthalene, respectively. Higher concentrations of VOCs were observed during the winter campaign, possibly due to slower dispersion, slower chemical transformations and/or the lengthy "cold start" period required by vehicles in the wintertime. A trajectory analysis showed that air masses

  9. Breathing zone particle size and lead concentration from sanding operations to remove lead based paints.

    Science.gov (United States)

    Alexander, W K; Carpenter, R L; Kimmel, E C

    1999-02-01

    The relationship between lead concentration in the dry film of lead based paints applied to steel bulkheads aboard ship, the lead concentration found in the air when the paint is removed by mechanical means, and blood lead concentrations of workers involved in lead based paint removal has not been well characterized. Intuitively a direct relationship must exist but confounding factors confuse the issue. Simultaneous sampling procedures from the same paint removal operation may differ by several orders of magnitude. The process from dried film to aerosol (airborne dust) exposure, and on to dose can be separated into two major phases; (1) generation of the dust and its transport through the air to the worker and (2) uptake and dose related factors within the body. Both phases involve complex interactions and there are a number of factors within each phase that significantly affect the potential lead dose for the worker. This study attempts to clarify the mechanisms involved in the generation and transportation of the dust to the worker by evaluating the relationship of a number of key factors on particle size and lead distribution within the aerosol dust generated when lead based paint is removed by sanding. The study examined the relationship between particle size in the dust and grit size of the abrasive. It also examined the distribution of lead within selected particle sizes. The Mass Median Aerodynamic Diameter (MMAD) was used as an indicator of change in the particle size distribution. Particle size distributions were evaluated using a TSI Aerodynamic Particle Sizer, a five stage cyclone and scanning electron microscopy. Lead distribution was determined using the five stage cyclone, and personal or area samples analyzed using inductively coupled plasma (ICP). Mass concentrations were evaluated using a MIE Mass Concentration Analyzer and gravimetric analysis of filter samples collected in the breathing zone. Student's t-tests were used to evaluate changes in

  10. Particle concentration measurement of virus samples using electrospray differential mobility analysis and quantitative amino acid analysis.

    Science.gov (United States)

    Cole, Kenneth D; Pease, Leonard F; Tsai, De-Hao; Singh, Tania; Lute, Scott; Brorson, Kurt A; Wang, Lili

    2009-07-24

    Virus reference materials are needed to develop and calibrate detection devices and instruments. We used electrospray differential mobility analysis (ES-DMA) and quantitative amino acid analysis (AAA) to determine the particle concentration of three small model viruses (bacteriophages MS2, PP7, and phiX174). The biological activity, purity, and aggregation of the virus samples were measured using plaque assays, denaturing gel electrophoresis, and size-exclusion chromatography. ES-DMA was developed to count the virus particles using gold nanoparticles as internal standards. ES-DMA additionally provides quantitative measurement of the size and extent of aggregation in the virus samples. Quantitative AAA was also used to determine the mass of the viral proteins in the pure virus samples. The samples were hydrolyzed and the masses of the well-recovered amino acids were used to calculate the equivalent concentration of viral particles in the samples. The concentration of the virus samples determined by ES-DMA was in good agreement with the concentration predicted by AAA for these purified samples. The advantages and limitations of ES-DMA and AAA to characterize virus reference materials are discussed.

  11. Submicron particle mass concentrations and sources in the Amazonian wet season (AMAZE-08)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Q.; Farmer, D. K.; Rizzo, L. V.; Pauliqueivis, T.; Kuwata, Mikinori; Karl, Thomas G.; Guenther, Alex B.; Allan, James D.; Coe, H.; Andreae, M. O.; Poeschl, U.; Jiminez, J. L.; Artaxo, Paulo; Martin, Scot T.

    2015-01-01

    Real-time mass spectra of non-refractory component of submicron aerosol particles were recorded in a tropical rainforest in the central Amazon basin during the wet season of 2008, as a part of the Amazonian Aerosol Characterization Experiment (AMAZE-08). Organic components accounted on average for more than 80% of the non-refractory submicron particle mass concentrations during the period of measurements. Ammonium was present in sufficient quantities to halfway neutralize sulfate. In this acidic, isoprene-dominated, low-NOx environment the high-resolution mass spectra as well as mass closures with ion chromatography measurements did not provide evidence for significant contributions of organosulfate species, at least at concentrations above uncertainty levels. Positive-matrix factorization of the time series of particle mass spectra identified four statistical factors to account for the variance of the signal intensities of the organic constituents: a factor HOA having a hydrocarbon-like signature and identified as regional emissions of primary organic material, a factor OOA-1 associated with fresh production of secondary organic material by a mechanism of BVOC oxidation followed by gas-to-particle conversion, a factor OOA-2 consistent with reactive uptake of isoprene oxidation products, especially epoxydiols by acidic particles, and a factor OOA-3 associated with long range transport and atmospheric aging. The OOA-1, -2, and -3 factors had progressively more oxidized signatures. Diameter-resolved mass spectral markers also suggested enhanced reactive uptake of isoprene oxidation products to the accumulation mode for the OOA-2 factor, and such size partitioning can be indicative of in-cloud process. The campaign-average factor loadings were in a ratio of 1.1:1.0 for the OOA-1 compared to the OOA-2 pathway, suggesting the comparable importance of gas-phase compared to particle-phase (including cloud waters) production pathways of secondary organic material during

  12. Hypothalamic neuropeptide Y (NPY) controls hepatic VLDL-triglyceride secretion in rats via the sympathetic nervous system

    NARCIS (Netherlands)

    Bruinstroop, E.; Pei, L.; Ackermans, M.T.; Foppen, E.; Borgers, A.J.F.; Kwakkel, J.; Alkemade, A.; Fliers, E.; Kalsbeek, A.

    2012-01-01

    Excessive secretion of triglyceride-rich very low-density lipoproteins (VLDL-TG) contributes to diabetic dyslipidemia. Earlier studies have indicated a possible role for the hypothalamus and autonomic nervous system in the regulation of VLDL-TG. In the current study, we investigated whether the auto

  13. Variability of aerosol particle number concentrations observed over the western Pacific in the spring of 2009

    Science.gov (United States)

    Takegawa, N.; Moteki, N.; Oshima, N.; Koike, M.; Kita, K.; Shimizu, A.; Sugimoto, N.; Kondo, Y.

    2014-12-01

    Airborne measurements of aerosols were conducted over the western Pacific in the spring of 2009 during the Aerosol Radiative Forcing in East Asia (A-FORCE) aircraft campaign. The A-FORCE flights intensively covered an important vertical-latitudinal range in the outflow region of East Asia (0-9 km altitude; 27°N-38°N). This paper presents the variability of aerosol particle number concentrations obtained by condensation particle counters and a Single-Particle Soot Photometer (SP2), with the focus on those in the free troposphere. The number concentration data include total condensation nuclei with particle diameters (dp) larger than 10 nm (total CN10), PM0.17-CN10 (dp 10-130 nm), and SP2 black carbon (NBC; dp 75-850 nm). Large increases in total CN10 that were not associated with NBC were observed in the free troposphere, suggesting influences from new particle formation (NPF). Statistical characteristics of total CN10, PM0.17-CN10, and NBC in the lower troposphere (LT; 0-3 km), middle troposphere (MT; 3-6 km), and upper troposphere (UT; 6-9 km) are investigated. The correlation between total CN10 and NBC, along with the ratio of PM0.17 to total CN10 and carbon monoxide mixing ratio (CO), is used to interpret the observed variability. The median concentrations of total CN10 and PM0.17-CN10 in the UT were higher than those in the MT by a factor of 1.4 and 1.6, respectively. We attribute the enhancements of CN10 in the UT to NPF. Possible mechanisms affecting NPF in the free troposphere are discussed.

  14. Particle size distribution and PAH concentrations of incense smoke in a combustion chamber

    Energy Technology Data Exchange (ETDEWEB)

    Yang, C.-R. [Department of Environmental Engineering National Cheng Kung University, 1, University Road, Tainan 70101, Taiwan (China); Sustainable Environment Research Center, National Cheng Kung University, 1, University Road, Tainan 70101, Taiwan (China); Lin, T.-C. [Department of Environmental Engineering National Cheng Kung University, 1, University Road, Tainan 70101, Taiwan (China) and Sustainable Environment Research Center, National Cheng Kung University, 1, University Road, Tainan 70101, Taiwan (China)]. E-mail: tachang@mail.ncku.edu.tw; Chang, F.-H. [Department of Information Management, Tzu Hui Institute of Technology, 367 SanMing Road, Pingtung, 926 Taiwan (China)

    2007-01-15

    The particle size distribution and the concentrations of polycyclic aromatic hydrocarbons (PAHs) in incense smoke were studied using a custom-designed combustion chamber. Among the nine types of incense investigated, the particle and the total PAH emission factors varied significantly. The average mass median aerodynamic diameter (MMAD) of the smoke aerosol was 262 {+-} 49 nm, which positively correlated to particle emission factor (mg/stick, p < 0.05). Coagulation was a major mechanism that dictates the MMAD of the smoke. The total toxic equivalency (the sum of the benzo[a]pyrene equivalent concentration) of the solid-phase PAHs (S-PAHs) was over 40 times higher than that of the corresponding gas-phase PAHs, indicating that the S-PAHs in incense smoke may pose potential health risk. Experiments show that each lowered percentage of total carbon content in the raw incense helped decrease the particle emission factor by 2.6 mg/g-incense, and the reduction of S-PAH emission factor ranged from 8.7 to 26% when the carbon content was lowered from 45 to 40%. - Emission profiles of PAHs from the nine types of studied incense appeared to share a common pattern.

  15. Shear-induced reaction-limited aggregation kinetics of brownian particles at arbitrary concentrations.

    Science.gov (United States)

    Zaccone, Alessio; Gentili, Daniele; Wu, Hua; Morbidelli, Massimo

    2010-04-07

    The aggregation of interacting brownian particles in sheared concentrated suspensions is an important issue in colloid and soft matter science per se. Also, it serves as a model to understand biochemical reactions occurring in vivo where both crowding and shear play an important role. We present an effective medium approach within the Smoluchowski equation with shear which allows one to calculate the encounter kinetics through a potential barrier under shear at arbitrary colloid concentrations. Experiments on a model colloidal system in simple shear flow support the validity of the model in the concentration range considered. By generalizing Kramers' rate theory to the presence of shear and collective hydrodynamics, our model explains the significant increase in the shear-induced reaction-limited aggregation kinetics upon increasing the colloid concentration.

  16. Reynolds number influence on preferential concentration of heavy particles in turbulent flows

    Energy Technology Data Exchange (ETDEWEB)

    Obligado, Martin; Missaoui, Mahrane; Cartellier, Alain; Bourgoin, Mickaeel [Laboratoire des Ecoulements Geophysiques et Industriels, CNRS/UJF/G-INP UMR5519, BP53, 38041 Grenoble cedex 9 (France); Monchaux, Romain, E-mail: mickael.bourgoin@hmg.inpg.fr [Unite de mecanique, Ecole Nationale Superieure de Techniques Avancees, ParisTech, Chemin de la Huniere, 91761, Palaiseau Cedex (France)

    2011-12-22

    We present a study of the preferential concentration and clustering in homogeneous and isotropic turbulence. Using Voronoie diagrams, we have formerly quantified preferential concentration as a function of the Stokes number in moderate turbulence conditions up to Reynolds number based on Taylor microscale of the order of R{sub {lambda}} {approx} 120. Using an active grid recently implemented in our windtunnel, we investigate in the present study, the effect of Reynolds number on particles clustering, in the range R{sub {lambda}} {approx} 200 - 400.

  17. Mea6 controls VLDL transport through the coordinated regulation of COPII assembly

    Science.gov (United States)

    Wang, Yaqing; Liu, Liang; Zhang, Hongsheng; Fan, Junwan; Zhang, Feng; Yu, Mei; Shi, Lei; Yang, Lin; Lam, Sin Man; Wang, Huimin; Chen, Xiaowei; Wang, Yingchun; Gao, Fei; Shui, Guanghou; Xu, Zhiheng

    2016-01-01

    Lipid accumulation, which may be caused by the disturbance in very low density lipoprotein (VLDL) secretion in the liver, can lead to fatty liver disease. VLDL is synthesized in endoplasmic reticulum (ER) and transported to Golgi apparatus for secretion into plasma. However, the underlying molecular mechanism for VLDL transport is still poorly understood. Here we show that hepatocyte-specific deletion of meningioma-expressed antigen 6 (Mea6)/cutaneous T cell lymphoma-associated antigen 5C (cTAGE5C) leads to severe fatty liver and hypolipemia in mice. Quantitative lipidomic and proteomic analyses indicate that Mea6/cTAGE5 deletion impairs the secretion of different types of lipids and proteins, including VLDL, from the liver. Moreover, we demonstrate that Mea6/cTAGE5 interacts with components of the ER coat protein complex II (COPII) which, when depleted, also cause lipid accumulation in hepatocytes. Our findings not only reveal several novel factors that regulate lipid transport, but also provide evidence that Mea6 plays a critical role in lipid transportation through the coordinated regulation of the COPII machinery. PMID:27311593

  18. The Binding Ability Analysis of the Normal VLDL Receptor and Its Mutant

    Institute of Scientific and Technical Information of China (English)

    QU Shen; FENG Ning; LIU Zhiguo; ZHOU Hua; DENG Yaozu; FENG Zongchen

    2001-01-01

    The ligand-binding domain of VLDL receptor contains eight imperfectly similar repeats.To discuss the contribution of each repeat to ligand binding, the RT-PCR technique was used to clone the VLDLR-cDNA from the heart muscle of Chinese people. Two recombinants were further constructed, which contained the full-length cDNA of VLDLR and the mutant lacking repeats 1-5.CHO cell line was transfected with two recombinants. The expression of VLDLR gene could be detected by RT-PCR from the CHO cells transfected with pCD-VR. The results of binding experiments showed that the ability of the CHO cells transfected with the full-length cDNA of VLDL-R binding DiI-labeled β-VLDL was higher than that of the CHO cells transfected with the mutant. Our findings indicated that human VLDL-R gene could be expressed effectively on CHO cells, and the receptor was almost inactivated when repeats1-5 were deleted.

  19. The effect of interaction between Lipoprotein Lipase and ApoVLDL-II ...

    African Journals Online (AJOL)

    GREGO

    2007-04-02

    Apr 2, 2007 ... non-significantly different in fat chicken. SNP in apoVLDL-II and ... stage in the control of adipose tissue accretion is the removal of triglycerides ..... of absorbed fat is the same, lower body fat deposition may be attributed to.

  20. Metformin lowers plasma triglycerides by promoting vldl-triglyceride clearance by brown adipose tissue in mice

    NARCIS (Netherlands)

    Geerling, J.J.; Boon, M.R.; Zon, G.C. van der; Berg, S.A.A. van den; Hoek, A.M. van den; Lombès, M.; Princen, H.M.G.; Havekes, L.M.; Rensen, P.C.N.; Guigas, B.

    2014-01-01

    Metformin is the first-line drug for the treatment of type 2 diabetes. Besides its well-characterized antihyperglycemic properties, metformin also lowers plasma VLDL triglyceride (TG). In this study, we investigated the underlying mechanisms in APOE*3-Leiden.CETP mice, a well-established model for h

  1. The Influence of Base Concentration on the Surface Particle of Lithium Aluminosilicate System

    Science.gov (United States)

    Nazri, I. M.; Asliza, M. A. Sri; Othman, R.

    2008-03-01

    The study of base concentration effect toward surface particles of lithium aluminosilicate glass ceramic system has been done by using NaOH solution. The parent glass with composition of 60% SiO2, 31% Li2O, 6% Al2O3 and 3% TiO2 in wt% was prepared by melting process at 1250 °C prior to quenching rapidly to room temperature. Sintering and crystallization process on this parent glass were carefully examined by Differential thermal analysis (DTA) and X-Ray Diffraction (XRD). Based on these analyses, the selected crystal has been chosen as a precursor material. There are two controlling parameter involved in this study i.e. NaOH concentration and leaching period. The morphology of the glass ceramic particle was observed by Field Emission Scanning Electron Microscope (FESEM). The result shows that by increasing the basic concentration as well as increasing the soaking leaching period, the tendency of glass ceramic particle to leach out is relatively highs.

  2. Concentrations, size distributions and temporal variations of fluorescent biological aerosol particles in southern tropical India

    Science.gov (United States)

    Valsan, Aswathy; Krishna R, Ravi; CV, Biju; Huffman, Alex; Poschl, Ulrich; Gunthe, Sachin

    2015-04-01

    Biological aerosols constitute a wide range of dead and alive biological materials and structures that are suspended in the atmosphere. They play an important role in the atmospheric physical, chemical and biological processes and health of living being by spread of diseases among humans, plants, and, animals. The atmospheric abundance, sources, physical properties of PBAPs as compared to non-biological aerosols, however, is poorly characterized. The Indian tropical region, where large fraction of the world's total population is residing, experiences a distinctive meteorological phenomenon by means of Indian Summer Monsoon (IMS). Thus, the properties and characteristics of biological aerosols are also expected to be very diverse over the Indian subcontinent depending upon the seasons. Here we characterize the number concentration and size distribution of Fluorescent Biological Aerosol Particles (FBAP) at a high altitude continental site, Munnar (10.09 N, 77.06 E; 1605 m asl) in South India during the South-West monsoon, which constitute around 80 percent of the annual rainfall in Munnar. Continuous three months measurements (from 01 June 2014 to 21 Aug 2104) FBAPs were carried out at Munnar using Ultra Violet Aerodynamic Particle Sizer (UVAPS) during IMS. The mean number and mass concentration of coarse FBAP averaged over the entire campaign was 1.7 x 10-2 cm-3 and 0.24 µg m-3 respectively, which corresponds to 2 percent and 6 percent of total aerosol particle number and mass concentration. In agreement to other previous measurements the number size distribution of FBAP also peaks at 3.2 micron indicating the strong presence of fungal spores. This was also supported by the Scanning Electron Microscopic analysis of bioaerosols on filter paper. They also displayed a strong diurnal cycle with maximum concentration occurring at early morning hours. During periods of heavy and continuous rain where the wind is consistently blowing from South-West direction it was

  3. Serum homocysteine is not independently associated with an atherogenic lipid profile: The Very Large Database of Lipids (VLDL-21) study.

    Science.gov (United States)

    Lupton, Joshua R; Quispe, Renato; Kulkarni, Krishnaji; Martin, Seth S; Jones, Steven R

    2016-06-01

    Hyperhomocysteinemia is an independent risk factor for cardiovascular disease, but the mechanism for this risk remains unclear. While reducing serum total homocysteine (tHcy) has been shown to decrease strokes, there is no evidence for an effect on myocardial infarctions in randomized controlled trials. This study aims to examine the relationship between tHcy and several lipid measures. Our analyses included 18,297 U.S. adults from the Very Large Database of Lipids who had an extended lipid panel including direct measurement of triglycerides (TG), and the cholesterol concentration of low-density lipoprotein (LDL-C), high-density lipoprotein (HDL-C), non-HDL-C, very low-density lipoprotein (VLDL-C), and remnant-lipoprotein cholesterol (RLP-C: IDL-C + VLDL3-C). Additional measurements were tHcy, hemoglobin A1c (HbA1c), insulin, creatinine, and blood urea nitrogen (BUN). Subjects were categorized into tHcy quartiles. Linear regression models were performed using lipids and tHcy as dependent and independent variables respectively, and further adjusted with age, sex, HbA1c, insulin, creatinine, and BUN levels in multivariable regression. In unadjusted analysis, levels of LDL-C (p lipids were eliminated (p-value range: 0.101-0.750) when controlling for age, sex, HbA1c, insulin, creatinine, and BUN. Although high levels of tHcy were associated with 2-6% higher TG-rich lipoproteins in unadjusted analysis, after adjustment for confounders our findings do not support the hypothesis that hyperhomocysteinemia is associated with an atherogenic lipid profile. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  4. Relating urban airborne particle concentrations to shipping using carbon based elemental emission ratios

    Science.gov (United States)

    Johnson, Graham R.; Juwono, Alamsyah M.; Friend, Adrian J.; Cheung, Hing-Cho; Stelcer, Eduard; Cohen, David; Ayoko, Godwin A.; Morawska, Lidia

    2014-10-01

    This study demonstrates a novel method for testing the hypothesis that variations in primary and secondary particle number concentration (PNC) in urban air are related to residual fuel oil combustion at a coastal port lying 30 km upwind, by examining the correlation between PNC and airborne particle composition signatures chosen for their sensitivity to the elemental contaminants present in residual fuel oil. Residual fuel oil combustion indicators were chosen by comparing the sensitivity of a range of concentration ratios to airborne emissions originating from the port. The most responsive were combinations of vanadium and sulphur concentration ([S], [V]) expressed as ratios with respect to black carbon concentration ([BC]). These correlated significantly with ship activity at the port and with the fraction of time during which the wind blew from the port. The average [V] when the wind was predominantly from the port was 0.52 ng m-3 (87%) higher than the average for all wind directions and 0.83 ng m-3 (280%) higher than that for the lowest vanadium yielding wind direction considered to approximate the natural background. Shipping was found to be the main source of V impacting urban air quality in Brisbane. However, contrary to the stated hypothesis, increases in PNC related measures did not correlate with ship emission indicators or ship traffic. Hence at this site ship emissions were not found to be a major contributor to PNC compared to other fossil fuel combustion sources such as road traffic, airport and refinery emissions.

  5. Evaluation of exposure risk in the weaving process of MWCNT-coated yarn with real-time particle concentration measurements and characterization of dust particles.

    Science.gov (United States)

    Takaya, Mitsutoshi; Ono-Ogasawara, Mariko; Shinohara, Yasushi; Kubota, Hisayo; Tsuruoka, Shuji; Koda, Shigeki

    2012-01-01

    Various applications of multiwalled carbon nanotubes (MWCNT) have been developed. One of these applications is an efficient sheet heating element that is woven from MWCNT-coated yarn. In this research, we assessed the exposure to MWCNT and/or the probability of particle release from broken MWCNT-coated yarn during the weaving process. This was accomplished using particle concentrations, microscopic observation, and carbon analysis. In the weaving process, neither an increase in the number of particles nor a difference in particle-size distribution was observed. In the scanning electron micrographic observation, nanosize MWCNT particles were not detected, but there were micron-size particles containing MWCNT as fragments of the yarn. Carbon analysis showed the concentration of micron-size particles containing MWCNT did not exceed 0.0053 mg-C/m(3) around the loom. This value was much lower than the respirable dust mass concentration. Most of micron-size particles seemed to originate from polyester yarn without MWCNT coating. It is recommended that workers use conventional (even not specialized for nanoparticles) personal protective equipment such as respirators and gloves to prevent exposure to respirable-size MWCNT-containing particles. The probability of MWCNT fall-off from the MWCNT-coated yarn was not detected by transmission electron microscopic observation of MWCNT-coated yarn before or after the weaving process.

  6. Analysis of the Hydrogen Reduction Rate of Magnetite Concentrate Particles in a Drop Tube Reactor Through CFD Modeling

    Science.gov (United States)

    Fan, Deqiu; Mohassab, Yousef; Elzohiery, Mohamed; Sohn, H. Y.

    2016-06-01

    A computational fluid dynamics (CFD) approach, coupled with experimental results, was developed to accurately evaluate the kinetic parameters of iron oxide particle reduction. Hydrogen reduction of magnetite concentrate particles was used as a sample case. A detailed evaluation of the particle residence time and temperature profile inside the reactor is presented. This approach eliminates the errors associated with assumptions like constant particle temperature and velocity while the particles travel down a drop tube reactor. The gas phase was treated as a continuum in the Eulerian frame of reference, and the particles are tracked using a Lagrangian approach in which the trajectory and velocity are determined by integrating the equation of particle motion. In addition, a heat balance on the particle that relates the particle temperature to convection and radiation was also applied. An iterative algorithm that numerically solves the governing coupled ordinary differential equations was developed to determine the pre-exponential factor and activation energy that best fit the experimental data.

  7. Multi-step process for concentrating magnetic particles in waste sludges

    Science.gov (United States)

    Watson, John L.

    1990-01-01

    This invention involves a multi-step, multi-force process for dewatering sludges which have high concentrations of magnetic particles, such as waste sludges generated during steelmaking. This series of processing steps involves (1) mixing a chemical flocculating agent with the sludge; (2) allowing the particles to aggregate under non-turbulent conditions; (3) subjecting the mixture to a magnetic field which will pull the magnetic aggregates in a selected direction, causing them to form a compacted sludge; (4) preferably, decanting the clarified liquid from the compacted sludge; and (5) using filtration to convert the compacted sludge into a cake having a very high solids content. Steps 2 and 3 should be performed simultaneously. This reduces the treatment time and increases the extent of flocculation and the effectiveness of the process. As partially formed aggregates with active flocculating groups are pulled through the mixture by the magnetic field, they will contact other particles and form larger aggregates. This process can increase the solids concentration of steelmaking sludges in an efficient and economic manner, thereby accomplishing either of two goals: (a) it can convert hazardous wastes into economic resources for recycling as furnace feed material, or (b) it can dramatically reduce the volume of waste material which must be disposed.

  8. Air Pressure-Assisted Centrifugal Dewatering of Concentrated Fine Sulfide Particles

    Directory of Open Access Journals (Sweden)

    R. Asmatulu

    2011-01-01

    Full Text Available An air pressure-assisted centrifugal dewatering method was developed and used for the dewatering of concentrated finesulfide particles, such as sphalerite, galena, and chalcopyrite. This filtration method was mainly designed to increase the filtration rate during the drainage cycle and, hence, produce drier filter cakes, which in turn could reduce the cost and emission problems/concerns of thermal dryers in the preparation plants. Several dewatering parameters, including applied pressure, centrifugal force (G-force, spin time, cake thickness, and surface hydrophobization, were tested to optimize the processing conditions. Test results showed that, at higher air pressure and centrifugal force, the cake moisture reduction was more than 70%, depending on the testing conditions. As a result, it can be-concluded that the novel filtration method effectively works on the dewatering of fine particles (–150 μm.

  9. Lipoprotein particle subclass profiles among metabolically healthy and unhealthy obese and non-obese adults: does size matter?

    Science.gov (United States)

    Phillips, Catherine M; Perry, Ivan J

    2015-10-01

    No data regards lipoprotein particle profiles in obese and non-obese metabolic health subtypes exist. We characterised lipoprotein size, particle and subclass concentrations among metabolically healthy and unhealthy obese and non-obese adults. Cross-sectional sample of 1834 middle-aged Irish adults were classified as obese (BMI ≥30 kg/m(2)) and non-obese (BMI Lipoprotein size, particle and subclass concentrations were determined using nuclear magnetic resonance (NMR) spectroscopy. Lipoprotein profiling identified a range of adverse phenotypes among the metabolically unhealthy individuals, regardless of BMI and metabolic health definition, including increased numbers of small low density lipoprotein (LDL) (P lipoprotein (HDL) particles (P lipoprotein (VLDL) particles (P lipoprotein related insulin resistance (P lipoprotein particle profiles, irrespective of BMI and metabolic health definition. These findings underscore the importance of maintaining a healthy lipid profile in the context of overall cardiometabolic health. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  10. Estimating particle sizes, concentrations, and total mass of ash in volcanic clouds using weather radar

    Science.gov (United States)

    Harris, D. M.; Rose, W. I., Jr.

    1983-12-01

    Radar observations of the March 19, 1982 ash eruption of Mount St. Helens were used to estimate the volume of the ash cloud (2000 + or - 500 cu km), the concentration of ash (0.2-0.6 g/cu m), and the total mass of ash erupted (3-10 x 10 to the 11th g). Previously published ashfall data for the May 18, 1980 Mount St. Helens eruption were studied using an inversion technique to estimate 6-hr mean particle concentration (3 g/cu m), the size distribution, the total ashfall mass (5 x 10 to the 14th g), and radar reflectivity factors for the ash cloud. Because volcanic ash clouds with particle concentrations of at least 0.2 g/cu m are produced in very small (in terms of total ashfall mass) eruptions of duration less than 1 min, volcanic ash clouds must be considered an extremely serious hazard to in-flight aircraft, regardless of the eruption magnitude.

  11. Time evolution of atmospheric particle number concentration during high-intensity pyrotechnic events

    Science.gov (United States)

    Crespo, Javier; Yubero, Eduardo; Nicolás, Jose F.; Caballero, Sandra; Galindo, Nuria

    2014-10-01

    The Mascletàs are high-intensity pyrotechnic events, typical of eastern Spanish festivals, in which thousands of firecrackers are burnt at ground level in an intense, short-time (festival in Alicante (southeastern Spain). Peak concentrations and dilution times observed throughout the Mascletàs have been compared to those measured when conventional aerial fireworks were launched 2 km away from the monitoring site. The impact of the Mascletàs on the total number concentration of particles larger than 0.3 μm was higher (maximum ˜2·104 cm-3) than that of fireworks (maximum ˜2·103 cm-3). The effect of fireworks depended on whether the dominant meteorological conditions favoured the transport of the plume to the measurement location. However, the time required for particle concentrations to return to background levels is longer and more variable for firework displays (minutes to hours) than for the Mascletàs (<25 min).

  12. Estimation of the particle concentration in hydraulic liquid by the in-line automatic particle counter based on the CMOS image sensor

    Science.gov (United States)

    Kornilin, Dmitriy V.; Kudryavtsev, Ilya A.; McMillan, Alison J.; Osanlou, Ardeshir; Ratcliffe, Ian

    2017-06-01

    Modern hydraulic systems should be monitored on the regular basis. One of the most effective ways to address this task is utilizing in-line automatic particle counters (APC) built inside of the system. The measurement of particle concentration in hydraulic liquid by APC is crucial because increasing numbers of particles should mean functional problems. Existing automatic particle counters have significant limitation for the precise measurement of relatively low concentration of particle in aerospace systems or they are unable to measure higher concentration in industrial ones. Both issues can be addressed by implementation of the CMOS image sensor instead of single photodiode used in the most of APC. CMOS image sensor helps to overcome the problem of the errors in volume measurement caused by inequality of particle speed inside of tube. Correction is based on the determination of the particle position and parabolic velocity distribution profile. Proposed algorithms are also suitable for reducing the errors related to the particles matches in measurement volume. The results of simulation show that the accuracy increased up to 90 per cent and the resolution improved ten times more compared to the single photodiode sensor.

  13. The effect of dust emissions from open storage piles to particle ambient concentration and human exposure.

    Science.gov (United States)

    Chalvatzaki, E; Aleksandropoulou, V; Glytsos, T; Lazaridis, M

    2012-12-01

    The current study focus on the determination of dust emissions from piles in open storage yards of a municipal solid waste (MSW) composting site and the subsequent atmospheric dust dispersion. The ISC3-ST (Industrial Source Complex Version 3 - Short Term) model was used for the evaluation of the PM(10) ambient concentrations associated with the dispersion of MSW compost dust emissions in air. Dust emission rates were calculated using the United States Environmental Protection Agency proposed dust resuspension formulation from open storage piles using local meteorological data. The dispersion modelling results on the spatial distribution of PM(10) source depletion showed that the maximum concentrations were observed at a distance 25-75 m downwind of the piles in the prevailing wind direction. Sensitivity calculations were performed also to reveal the effect of the compost pile height, the friction velocity and the receptor height on the ambient PM(10) concentration. It was observed that PM(10) concentrations (downwind in the prevailing wind direction) increased with increasing the friction velocity, increasing the pile height (for distances greater than 125 m from the source) and decreasing the receptor height (for distances greater than 125 m from the source). Furthermore, the results of ISC3-ST were analysed with the ExDoM (Exposure Dose Model) human exposure model. The ExDoM is a model for calculating the human exposure and the deposition dose, clearance, and finally retention of aerosol particles in the human respiratory tract (RT). PM(10) concentration at the composting site was calculated as the sum of the concentration from compost pile dust resuspension and the background concentration. It was found that the exposure to PM(10) and deposited lung dose for an adult Caucasian male who is not working at the composting site is less by 20-74% and 29-84%, respectively, compared to those for a worker exposed to PM concentrations at the composting site.

  14. Time-series forecasting of pollutant concentration levels using particle swarm optimization and artificial neural networks

    Directory of Open Access Journals (Sweden)

    Francisco S. de Albuquerque Filho

    2013-01-01

    Full Text Available This study evaluates the application of an intelligent hybrid system for time-series forecasting of atmospheric pollutant concentration levels. The proposed method consists of an artificial neural network combined with a particle swarm optimization algorithm. The method not only searches relevant time lags for the correct characterization of the time series, but also determines the best neural network architecture. An experimental analysis is performed using four real time series and the results are shown in terms of six performance measures. The experimental results demonstrate that the proposed methodology achieves a fair prediction of the presented pollutant time series by using compact networks.

  15. Ultrasonic device for real-time sewage velocity and suspended particles concentration measurements.

    Science.gov (United States)

    Abda, F; Azbaid, A; Ensminger, D; Fischer, S; François, P; Schmitt, P; Pallarès, A

    2009-01-01

    In the frame of a technological research and innovation network in water and environment technologies (RITEAU, Réseau de Recherche et d'Innovation Technologique Eau et Environnement), our research group, in collaboration with industrial partners and other research institutions, has been in charge of the development of a suitable flowmeter: an ultrasonic device measuring simultaneously the water flow and the concentration of size classes of suspended particles. Working on the pulsed ultrasound principle, our multi-frequency device (1 to 14 MHz) allows flow velocity and water height measurement and estimation of suspended solids concentration. Velocity measurements rely on the coherent Doppler principle. A self developed frequency estimator, so called Spectral Identification method, was used and compared to the classical Pulse-Pair method. Several measurements campaigns on one wastewater collector of the French city of Strasbourg gave very satisfactory results and showed smaller standard deviation values for the Doppler frequency extracted by the Spectral Identification method. A specific algorithm was also developed for the water height measurements. It relies on the water surface acoustic impedance rupture and its peak localisation and behaviour in the collected backscattering data. This algorithm was positively tested on long time measurements on the same wastewater collector. A large part of the article is devoted to the measurements of the suspended solids concentrations. Our data analysis consists in the adaptation of the well described acoustic behaviour of sand to the behaviour of wastewater particles. Both acoustic attenuation and acoustic backscattering data over multiple frequencies are analyzed for the extrapolation of size classes and respective concentrations. Under dry weather conditions, the massic backscattering coefficient and the overall size distribution showed similar evolution whatever the measurement site was and were suggesting a global

  16. On the peculiarities of LDA method in two-phase flows with high concentrations of particles

    Science.gov (United States)

    Poplavski, S. V.; Boiko, V. M.; Nesterov, A. U.

    2016-10-01

    Popular applications of laser Doppler anemometry (LDA) in gas dynamics are reviewed. It is shown that the most popular method cannot be used in supersonic flows and two-phase flows with high concentrations of particles. A new approach to implementation of the known LDA method based on direct spectral analysis, which offers better prospects for such problems, is presented. It is demonstrated that the method is suitable for gas-liquid jets. Owing to the progress in laser engineering, digital recording of spectra, and computer processing of data, the method is implemented at a higher technical level and provides new prospects of diagnostics of high-velocity dense two-phase flows.

  17. Effects of concentrated ambient particles on normal and hypersecretory airways in rats.

    Science.gov (United States)

    Harkema, Jack R; Keeler, Gerald; Wagner, James; Morishita, Masako; Timm, Edward; Hotchkiss, Jon; Marsik, Frank; Dvonch, Timothy; Kaminski, Norbert; Barr, Edward

    2004-08-01

    Detroit during the summer months when particulate air pollution is usually high (July and September 2000). We monitored the outdoor air pollution in this community daily, and exposed normal and compromised rats to concentrated PM2.5 from this local urban atmosphere. Rats in the inhalation studies were exposed for 1 day or for 4 or 5 consecutive days (10 hours/day) to either filtered air (controls) or concentrated ambient particles (CAPs) delivered by a Harvard ambient fine particle concentrator. Rats were killed 24 hours after the end of the exposure. Biochemical, morphometric, and molecular techniques were used to identify airway epithelial and inflammatory responses to CAPs. Lung lobes were also either intratracheally lavaged with saline to determine cellular composition and protein in bronchoalveolar lavage fluid (BALF) or removed for analysis by inductively coupled plasma-mass spectrometry (ICPMS) to detect retention of ambient PM2.5--derived trace elements. The Harvard concentrator effectively concentrated the fine ambient particles from this urban atmosphere (10-30 times) without significantly changing the major physicochemical features of the atmospheric particles. Daily CAPs mass concentrations during the 10-hour exposure period (0800-1800) in July ranged from 16 to 895 microg/m3 and in September ranged from 81 to 755 microg/m3. In general, chemical characteristics of ambient particles were conserved through the concentrator into the exposure chamber. Single or repeated exposures to CAPs did not cause adverse effects in the nasal or pulmonary airways of healthy F344 or BN rats. In addition, CAPs-related toxicity was not observed in F344 rats pretreated with bacterial endotoxin. Variable airway responses to CAPs exposure were observed in BN rats with preexisting allergic airway disease induced by OVA sensitization and challenge. Only OVA-challenged BN rats exposed to CAPs for 5 consecutive days in September 2000 had significant increases in airway mucosubstances

  18. Calculations of critical micelle concentration by dissipative particle dynamics simulations: the role of chain rigidity.

    Science.gov (United States)

    Lee, Ming-Tsung; Vishnyakov, Aleksey; Neimark, Alexander V

    2013-09-05

    Micelle formation in surfactant solutions is a self-assembly process governed by complex interplay of solvent-mediated interactions between hydrophilic and hydrophobic groups, which are commonly called heads and tails. However, the head-tail repulsion is not the only factor affecting the micelle formation. For the first time, we present a systematic study of the effect of chain rigidity on critical micelle concentration and micelle size, which is performed with the dissipative particle dynamics simulation method. Rigidity of the coarse-grained surfactant molecule was controlled by the harmonic bonds set between the second-neighbor beads. Compared to flexible molecules with the nearest-neighbor bonds being the only type of bonded interactions, rigid molecules exhibited a lower critical micelle concentration and formed larger and better-defined micelles. By varying the strength of head-tail repulsion and the chain rigidity, we constructed two-dimensional diagrams presenting how the critical micelle concentration and aggregation number depend on these parameters. We found that the solutions of flexible and rigid molecules that exhibited approximately the same critical micelle concentration could differ substantially in the micelle size and shape depending on the chain rigidity. With the increase of surfactant concentration, primary micelles of more rigid molecules were found less keen to agglomeration and formation of nonspherical aggregates characteristic of flexible molecules.

  19. An olive oil-rich diet results in higher concentrations of LDL cholesterol and a higher number of LDL subfraction particles than rapeseed oil and sunflower oil diets.

    Science.gov (United States)

    Pedersen, A; Baumstark, M W; Marckmann, P; Gylling, H; Sandström, B

    2000-12-01

    We investigated the effect of olive oil, rapeseed oil, and sunflower oil on blood lipids and lipoproteins including number and lipid composition of lipoprotein subclasses. Eighteen young, healthy men participated in a double-blinded randomized cross-over study (3-week intervention period) with 50 g of oil per 10 MJ incorporated into a constant diet. Plasma cholesterol, triacylglycerol, apolipoprotein B, and very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), and low density lipoprotein (LDL) cholesterol concentrations were 10;-20% higher after consumption of the olive oil diet compared with the rapeseed oil and sunflower oil diets [analysis of variance (ANOVA), P sunflower oil diets (ANOVA, P sunflower oil (ANOVA, P sunflower oil had more favorable effects on blood lipids and plasma apolipoproteins as well as on the number and lipid content of LDL subfractions compared with olive oil. Some of the differences may be attributed to differences in the squalene and phytosterol contents of the oils.

  20. Structure and thermorheology of concentrated pluronic copolymer micelles in the presence of laponite particles.

    Science.gov (United States)

    Boucenna, Imane; Royon, Laurent; Colinart, Pierre; Guedeau-Boudeville, Marie-Alice; Mourchid, Ahmed

    2010-09-21

    Small-angle neutron scattering and thermorheology techniques are used to investigate in detail the effect of laponite particles in aqueous solutions of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), PEO-PPO-PEO, block copolymers in the concentrated regime. At high polymer concentration or temperature, the micellar solutions exhibit a phase transition from fluid to crystal due to crowding of the micelles. The addition of laponite is found to disturb this phase transition. The adsorption of the copolymer unimers onto laponite in large amounts describes these findings. It is shown that the preferred adsorption of the copolymer chains results in a sufficient increase in free volume for the remaining micelles to yield the observed enhancement of the structural disorder.

  1. Exposure to fine particulate, black carbon, and particle number concentration in transportation microenvironments

    Science.gov (United States)

    Morales Betancourt, R.; Galvis, B.; Balachandran, S.; Ramos-Bonilla, J. P.; Sarmiento, O. L.; Gallo-Murcia, S. M.; Contreras, Y.

    2017-05-01

    This research determined intake dose of fine particulate matter (PM2.5), equivalent black carbon (eBC), and number of sub-micron particles (Np) for commuters in Bogotá, Colombia. Doses were estimated through measurements of exposure concentration, a surrogate of physical activity, as well as travel times and speeds. Impacts of travel mode, traffic load, and street configuration on dose and exposure were explored. Three road segments were selected because of their different traffic loads and composition, and dissimilar street configuration. The transport modes considered include active modes (walking and cycling) and motorized modes (bus, car, taxi, and motorcycle). Measurements were performed simultaneously in the available modes at each road segment. High average eBC concentrations were observed throughout the campaign, ranging from 20 to 120 μgm-3 . Commuters in motorized modes experienced significantly higher exposure concentrations than pedestrians and bicyclists. The highest average concentrations of PM2.5, eBC , and Np were measured inside the city's Bus Rapid Transit (BRT) system vehicles. Pedestrians and bicycle users in an open street configuration were exposed to the lowest average concentrations of PM2.5 and eBC , six times lower than those experienced by commuters using the BRT in the same street segment. Pedestrians experienced the highest particulate matter intake dose in the road segments studied, despite being exposed to lower concentrations than commuters in motorized modes. Average potential dose of PM2.5 and eBC per unit length traveled were nearly three times higher for pedestrians in a street canyon configuration compared to commuters in public transport. Slower travel speed and elevated inhalation rates dominate PM dose for pedestrians. The presence of dedicated bike lanes on sidewalks has a significant impact on reducing the exposure concentration for bicyclists compared to those riding in mixed traffic lanes. This study proposes a simple

  2. Shear Rheology of Suspensions of Porous Zeolite Particles in Concentrated Polymer Solutions

    Science.gov (United States)

    Olanrewaju, Kayode O.; Breedveld, Victor

    2008-07-01

    We present experimental data on the shear rheology of Ultem (polyetherimide)/NMP(l-methyl-2-pyrrolidinone) solutions with and without suspended surface-modified porous/nonporous zeolite (ZSM-5) particles. We found that the porous zeolite suspensions have relative viscosities that significantly exceed the Krieger-Dougherty predictions for hard sphere suspensions. The major origin of this discrepancy is the selective absorption of NMP solvent into the zeolite pores, which raises both the polymer concentration and the particle volume fraction, thus enhancing both the viscosity of the continuous phase Ultem/NMP polymer solution and the particle contribution to the suspension viscosity. Other factors, such as zeolite non-sphericity and specific interactions with Ultem polymer, contribute to the suspension viscosity to a lesser extent. We propose a predictive model for the viscosity of porous zeolite suspensions by incorporating an absorption parameter, α, into the Krieger-Dougherty model. We also propose independent approaches to determine α. The first one is indirect and based on zeolite density/porosity data, assuming that all pores will be filled with solvent. The other method is based on our experimental data, by comparing the viscosity data of porous versus non-porous zeolite suspensions. The different approaches are compared.

  3. Contribution of feldspar and marine organic aerosols to global ice nucleating particle concentrations

    Science.gov (United States)

    Vergara-Temprado, Jesús; Murray, Benjamin J.; Wilson, Theodore W.; O'Sullivan, Daniel; Browse, Jo; Pringle, Kirsty J.; Ardon-Dryer, Karin; Bertram, Allan K.; Burrows, Susannah M.; Ceburnis, Darius; DeMott, Paul J.; Mason, Ryan H.; O'Dowd, Colin D.; Rinaldi, Matteo; Carslaw, Ken S.

    2017-03-01

    Ice-nucleating particles (INPs) are known to affect the amount of ice in mixed-phase clouds, thereby influencing many of their properties. The atmospheric INP concentration changes by orders of magnitude from terrestrial to marine environments, which typically contain much lower concentrations. Many modelling studies use parameterizations for heterogeneous ice nucleation and cloud ice processes that do not account for this difference because they were developed based on INP measurements made predominantly in terrestrial environments without considering the aerosol composition. Errors in the assumed INP concentration will influence the simulated amount of ice in mixed-phase clouds, leading to errors in top-of-atmosphere radiative flux and ultimately the climate sensitivity of the model. Here we develop a global model of INP concentrations relevant for mixed-phase clouds based on laboratory and field measurements of ice nucleation by K-feldspar (an ice-active component of desert dust) and marine organic aerosols (from sea spray). The simulated global distribution of INP concentrations based on these two species agrees much better with currently available ambient measurements than when INP concentrations are assumed to depend only on temperature or particle size. Underestimation of INP concentrations in some terrestrial locations may be due to the neglect of INPs from other terrestrial sources. Our model indicates that, on a monthly average basis, desert dusts dominate the contribution to the INP population over much of the world, but marine organics become increasingly important over remote oceans and they dominate over the Southern Ocean. However, day-to-day variability is important. Because desert dust aerosol tends to be sporadic, marine organic aerosols dominate the INP population on many days per month over much of the mid- and high-latitude Northern Hemisphere. This study advances our understanding of which aerosol species need to be included in order to

  4. Contribution of feldspar and marine organic aerosols to global ice nucleating particle concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Vergara-Temprado, Jesús; Murray, Benjamin J.; Wilson, Theodore W.; O& amp; apos; Sullivan, Daniel; Browse, Jo; Pringle, Kirsty J.; Ardon-Dryer, Karin; Bertram, Allan K.; Burrows, Susannah M.; Ceburnis, Darius; DeMott, Paul J.; Mason, Ryan H.; O& amp; apos; Dowd, Colin D.; Rinaldi, Matteo; Carslaw, Ken S.

    2017-01-01

    Ice-nucleating particles (INPs) are known to affect the amount of ice in mixed-phase clouds, thereby influencing many of their properties. The atmospheric INP concentration changes by orders of magnitude from terrestrial to marine environments, which typically contain much lower concentrations. Many modelling studies use parameterizations for heterogeneous ice nucleation and cloud ice processes that do not account for this difference because they were developed based on INP measurements made predominantly in terrestrial environments without considering the aerosol composition. Errors in the assumed INP concentration will influence the simulated amount of ice in mixed-phase clouds, leading to errors in top-of-atmosphere radiative flux and ultimately the climate sensitivity of the model. Here we develop a global model of INP concentrations relevant for mixed-phase clouds based on laboratory and field measurements of ice nucleation by K-feldspar (an ice-active component of desert dust) and marine organic aerosols (from sea spray). The simulated global distribution of INP concentrations based on these two species agrees much better with currently available ambient measurements than when INP concentrations are assumed to depend only on temperature or particle size. Underestimation of INP concentrations in some terrestrial locations may be due to the neglect of INPs from other terrestrial sources. Our model indicates that, on a monthly average basis, desert dusts dominate the contribution to the INP population over much of the world, but marine organics become increasingly important over remote oceans and they dominate over the Southern Ocean. However, day-to-day variability is important. Because desert dust aerosol tends to be sporadic, marine organic aerosols dominate the INP population on many days per month over much of the mid- and high-latitude Northern Hemisphere. This study advances our understanding of which aerosol species need to be included in order to

  5. Mass Concentration and Mineralogical Characteristics Aerosol Particles Collected at Dunhuang During ACE-Asia

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment (ACE-Asia). The mean mass concentrations of total suspended particle matter during the spring of 2001 and 2002 were 317 μg m-3 and 307 μg m-3, respectively. Eleven dust storm events were observed with a mean aerosol concentration of 1095 μg m-3, while the non-dusty days with calm or weak wind speed had a background aerosol loading of 196 μg m-3 on average in the springtime.The main minerals detected in the aerosol samples by X-ray diffraction were illite, kaolinite, chlorite, quartz,feldspar, calcite and dolomite. Gypsum, halite and amphibole were also detected in a few samples. The mineralogical data also show that Asian dust is characterized by a kaolinite to chlorite (K/C) ratio lower than 1 whereas Saharan dust exhibits a K/C ratio larger than 2. Air mass back-trajectory analysis show that three families of pathways are associated with the aerosol particle transport to Dunhuang, but these have similar K/C ratios, which further demonstrates that the mineralogical characteristics of Asian dust are different from African dust.

  6. Determination of kinetic effects on particle size and concentration: instruction for scale up

    Science.gov (United States)

    Zhang, Ling; Nakamura, Hiroyuki; Lee, Changi; Uehara, Masato; Maeda, Hideaki

    2011-10-01

    Increasing the synthesis scale is one of the most important issues in nanocrystal synthesis. The main difference between small and large reactor is their thermal transfer rate which is reported to have great effects on particle nucleation and growth. In this paper, CdSe Quantum dots synthesis as was used as a model to investigate the heating rate effects in a microreactor system capable of precisely controlling the temperature and heating rate. Results showed that heating rate effects highly depended on the synthesis parameters. For example, in 5% Dodecanamine (DDA) case, there was no heating rate effect; while in the case of 20% DDA case, heating rate could affect both particle size distribution and morphology. Test experiments to demonstrate the up-scalability have been conducted and the results showed that products synthesized by batch reactor were comparable with microreactor products: Batch reactor gave same product when the DDA concentration was 5% but quite different product when the DDA concentration was 20%, compared with microreactor products. The data on the effects of heating rate obtained by this set up have high reliability and enable us to choose the proper method to increase the synthesis scale.

  7. Real-time measurements of suspended sediment concentration and particle size using five techniques

    Science.gov (United States)

    Felix, D.; Albayrak, I.; Abgottspon, A.; Boes, R. M.

    2016-11-01

    Fine sediments are important in the design and operation of hydropower plants (HPPs), in particular with respect to sediment management and hydro-abrasive erosion in hydraulic machines. Therefore, there is a need for reliable real-time measurements of suspended sediment mass concentration (SSC) and particle size distribution (PSD). The following instruments for SSC measurements were investigated in a field study during several years at the HPP Fieschertal in the Swiss Alps: (1) turbidimeters, (2) a Laser In-Situ Scattering and Trans- missometry instrument (LISST), (3) a Coriolis Flow and Density Meter (CFDM), (4) acoustic transducers, and (5) pressure sensors. LISST provided PSDs in addition to concentrations. Reference SSCs were obtained by gravimetrical analysis of automatically taken water samples. In contrast to widely used turbidimeters and the single-frequency acoustic method, SSCs obtained from LISST, the CFDM or the pressure sensors were less or not affected by particle size variations. The CFDM and the pressure sensors allowed measuring higher SSC than the optical or the acoustic techniques (without dilution). The CFDM and the pressure sensors were found to be suitable to measure SSC ≥ 2 g/l. In this paper, the measuring techniques, instruments, setup, methods for data treatment, and selected results are presented and discussed.

  8. Status of respirable dust particle (RDP) concentration--a case study in Chennai city.

    Science.gov (United States)

    Senthilnathan, T

    2005-06-01

    Air pollution has been aggravated by developments that typically occur, as countries become industrialised and higher levels of energy consumption. Respirable dust particles (RDP) is a general term for tiny air borne particles (under 10 microns PM 10) and it is categorised as critical primary air pollutant. Finer particulate matter less than 10 micron size have been identified as potential health hazard for human beings. A case study was carried out to assess RDP concentration present in the ambient air in Chennai city during the year 2000-2002. The study was conducted at Theagaraya nagar (T. Nagar), a most important commercial shopping place. The observed RDP concentrations are made statistical analysis and a high value of 607.1 microg/m(3) is recorded during October 2001. It is also found that 90% of the observed values exceed the recommended values of National Ambient Air Quality Standards (NAAQS). The important finding of this research work is that the RDP data collected every year from this sampling station were found to give best fit for cubic equations which are very useful for analysing future trends.

  9. Control of aerosol contaminants in indoor air: combining the particle concentration reduction with microbial inactivation.

    Science.gov (United States)

    Grinshpun, Sergey A; Adhikari, Atin; Honda, Takeshi; Kim, Ki Youn; Toivola, Mika; Rao, K S Ramchander; Reponen, Tiina

    2007-01-15

    An indoor air purification technique, which combines unipolar ion emission and photocatalytic oxidation (promoted by a specially designed RCI cell), was investigated in two test chambers, 2.75 m3 and 24.3 m3, using nonbiological and biological challenge aerosols. The reduction in particle concentration was measured size selectively in real-time, and the Air Cleaning Factor and the Clean Air Delivery Rate (CADR) were determined. While testing with virions and bacteria, bioaerosol samples were collected and analyzed, and the microorganism survival rate was determined as a function of exposure time. We observed that the aerosol concentration decreased approximately 10 to approximately 100 times more rapidly when the purifier operated as compared to the natural decay. The data suggest that the tested portable unit operating in approximately 25 m3 non-ventilated room is capable to provide CADR-values more than twice as great than the conventional closed-loop HVAC system with a rating 8 filter. The particle removal occurred due to unipolar ion emission, while the inactivation of viable airborne microorganisms was associated with photocatalytic oxidation. Approximately 90% of initially viable MS2 viruses were inactivated resulting from 10 to 60 min exposure to the photocatalytic oxidation. Approximately 75% of viable B. subtilis spores were inactivated in 10 min, and about 90% or greater after 30 min. The biological and chemical mechanisms that led to the inactivation of stress-resistant airborne viruses and bacterial spores were reviewed.

  10. Association between the concentration of fine particles in the atmosphere and acute respiratory diseases in children

    Directory of Open Access Journals (Sweden)

    Antônio Paula Nascimento

    Full Text Available ABSTRACT OBJECTIVE To analyze the association between fine particulate matter concentration in the atmosphere and hospital care by acute respiratory diseases in children. METHODS Ecological study, carried out in the region of Grande Vitória, Espírito Santo, in the winter (June 21 to September 21, 2013 and summer (December 21, 2013 to March 19, 2014. We assessed data of daily count for outpatient care and hospitalization by respiratory diseases (ICD-10 in children from zero to 12 years in three hospitals in the Region of Grande Vitória. For collecting fine particulate matter, we used portable samplers of particles installed in six locations in the studied region. The Generalized Additive Model with Poisson distribution, fitted for the effects of predictor covariates, was used to evaluate the relationship between respiratory outcomes and concentration of fine particulate matter. RESULTS The increase of 4.2 µg/m3 (interquartile range in the concentration of fine particulate matter increased in 3.8% and 5.6% the risk of medical care or hospitalization, respectively, on the same day and with six-day lag from the exposure. CONCLUSIONS We identified positive association between outpatient care and hospitalizations of children under 12 years due to acute respiratory diseases and the concentration of fine particulate matter in the atmosphere.

  11. Increased large VLDL particles confer elevated cholesteryl ester transfer in diabetes

    NARCIS (Netherlands)

    Dullaart, Robin P. F.; de Vries, Rindert; Kwakernaak, Arjan J.; Perton, Frank; Dallinga-Thie, Geesje M.

    2015-01-01

    BackgroundPlasma cholesteryl ester transfer (CET), reflecting transfer of cholesteryl esters from high density lipoproteins (HDL) towards apolipoprotein B-containing lipoproteins, may promote atherosclerosis development, and is elevated in Type 2 diabetes mellitus (T2DM). We determined the extent to

  12. Increased large VLDL particles confer elevated cholesteryl ester transfer in diabetes

    NARCIS (Netherlands)

    Dullaart, Robin P. F.; de Vries, Rindert; Kwakernaak, Arjan J.; Perton, Frank; Dallinga-Thie, Geesje M.

    BackgroundPlasma cholesteryl ester transfer (CET), reflecting transfer of cholesteryl esters from high density lipoproteins (HDL) towards apolipoprotein B-containing lipoproteins, may promote atherosclerosis development, and is elevated in Type 2 diabetes mellitus (T2DM). We determined the extent to

  13. Composition of human VLDL triacylglycerols after ingestion of olive oil and high oleic sunflower oil.

    Science.gov (United States)

    Ruiz-Gutiérrez, V; Morgado, N; Prada, J L; Pérez-Jiménez, F; Muriana, F J

    1998-03-01

    This work was undertaken to determine the effect of diets enriched with olive oil or high oleic sunflower oil on very low density lipoprotein (VLDL) triacylglycerol composition of healthy human subjects. Both oils contain a similar proportion of monounsaturated fatty acids (MUFA) but differ in their triacylglycerol composition. All 22 human subjects initially consumed a low fat, high carbohydrate diet as recommended by the National Cholesterol Education Program (NCEP-I). They then consumed the two experimental oils (40% dietary energy) in a crossover design. The olive oil and high oleic sunflower oil diets resulted in significant increases in palmitoleic (55%, P 100%, P sunflower oil diet increased the content of stearic acid (60%, P 100%, P sunflower oil diet). Intake of olive oil, in particular, significantly decreased the content of sn-glycerol-tripalmitate (36%, P sunflower oil diets. In addition, olive oil, but not high oleic sunflower oil, further contributed to VLDL triacylglycerols that contained alpha-linolenic and docosahexaenoic acids acylated in the sn-2 position. These data suggest that differences in the composition of VLDL triacylglycerols may be of major importance in explaining the beneficial effects of dietary olive oil in reducing the atherogenic risk profile in healthy subjects.

  14. Overproduction of a kinetic subclass of VLDL-apoB, and direct catabolism of VLDL-apoB in human endogenous hypertriglyceridemia: an analytical model solution of tracer data

    Energy Technology Data Exchange (ETDEWEB)

    Eaton, R.P.; Allen, R.C.; Schade, D.S.

    1983-10-01

    To investigate the participation of the major apoprotein involved in triglyceride transport in the pathogenesis of endogenous hypertriglyceridemia, five kinetic studies of apoprotein B were conducted in volunteer normolipidemic subjects and six studies in four patients with endogenous hypertriglyceridemia. The transport of apoprotein B within four kinetic subclasses of very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL), and low density lipoprotein (LDL) was studied by injection of (/sup 75/Se)selenomethionine. A 24-fold increase in the entry of newly synthesized apoprotein B at the initial kinetic subclass of the four-compartment VLDL delipidation sequence characterized the hypertriglyceridemic studies relative to normal subjects. Moreover, approximately 75 mg/kg per day of VLDL-B turnover reflected direct catabolism independent of conversion to IDL and/or to LDL, in contrast to the 8 mg/kg per day observed in controls. IDL-B was derived from VLDL-B in both normal and hypertriglyceridemic subjects, and was responsible for greater than 70% of all LDL-B synthesis. LDL-B pool size and turnover were indistinguishable in hypertriglyceridemic subjects from that observed in normal subjects. These studies suggest that two kinetic phenomena may characterize the pathophysiology of endogenous hypertriglyceridemia: a) over-production of apoB within a kinetic subclass of VLDL and b) preferential catabolism of hypertriglyceridemic VLDL without prior conversion to IDL/LDL.

  15. Rheology and Structure of Concentrated Suspensions of Hard Spheres. Shear Induced Particle Migration

    Science.gov (United States)

    Mills, P.; Snabre, P.

    1995-10-01

    The apparent shear viscosity, in the non-Brownian limit, for a homogeneous suspension of monodispersed hard spheres in systems ranging from dilute to concentrated was previously established. From an estimation of the viscous dissipation. We use the inter-particle distance dependence of the shear viscosity for determining the components of a local stress tensor associated with the transient network of particles for the volume fraction above the percolation threshold. For this purpose, we develop a model based on lubrication forces between colliding particles for coupling the particle stress tensor to the stress tensor of the suspension considered as an effective medium. In the case of non-uniform flows with low shear rate regions, it is necessary to introduce a non-local stress tensor since the stress can be directly transmitted by the network of particles over a correlation length larger than the particle diameter. This approach shows ... A partir d'une estimation de la dissipation visqueuse, nous avons précedemment évalué la viscosité apparente de cisaillement des suspensions homogènes de sphères dures monodisperses et non Browniennes dans les systèmes dilués ou concentrés. Nos utilisons la dépendance de la viscosité de cisaillement avec la distance moyenne entre les particules pour déterminer les composantes d'un tenseur local de contraintes associé à l'amas transitoire de particlues au dessus de la fraction volumique critique de percolation. Nous developpons pour cela un modèle basé sur les forces de lubrification s'exerçant au cours des collisions entre les particules afin de coupler le tenseur local de contraintes associé aux particules et le tenseur des contraintes dans la suspension assimilée à un milieu effectif. Dans le cas des écoulements non uniformes présentant des zones de faible cisaillement, il est nécessaire de considérer un tenseur non local des contraintes car les forces peuvent alors se transmettre directement à travers l

  16. Estimation of particle concentration profiles in a three-phase fluidized bed from experimental data and using the wake model

    Directory of Open Access Journals (Sweden)

    Knesebeck A.

    2004-01-01

    Full Text Available Particles with a size distribution in the range of 34 to 468 µm were fluidized in a three-phase bed using low liquid and gas velocities. Particle size distribution and pressure profile measurements were carried out at different locations in the bed in order to study the influence of fluid velocities on segregation and dispersion of particles in different size classes. The influence of gas velocity on particle mixing was analyzed in terms of internal solid fluxes, calculated by means of the wake model. Based on the experimental results, different particle distribution patterns were identified. Although no significant tendencies were observed for radial profiles, particles of different sizes have significantly different axial profiles, which are mainly affected by the velocity of the liquid phase. Thus, depending on the liquid velocity, smaller particles reach a maximum concentration at different bed heights.

  17. Concentration levels and source apportionment of ultrafine particles in road microenvironments

    Science.gov (United States)

    Argyropoulos, G.; Samara, C.; Voutsa, D.; Kouras, A.; Manoli, E.; Voliotis, A.; Tsakis, A.; Chasapidis, L.; Konstandopoulos, A.; Eleftheriadis, K.

    2016-03-01

    A mobile laboratory unit (MOBILAB) with on-board instrumentation (Scanning Mobility Particle Sizer, SMPS; Ambient NOx analyzer) was used to measure size-resolved particle number concentrations (PNCs) of quasi-ultrafine particles (UFPs, 9-372 nm), along with NOx, in road microenvironments. On-road measurements were carried out in and around a large Greek urban agglomeration, the Thessaloniki Metropolitan Area (TMA). Two 2-week measurement campaigns were conducted during the warm period of 2011 and the cold period of 2012. During each sampling campaign, MOBILAB was driven through a 5-day inner-city route and a second 5-day external route covering in total a wide range of districts (urban, urban background, industrial and residential), and road types (major and minor urban roads, freeways, arterial and interurban roads). All routes were conducted during working days, in morning and in afternoon hours under real-world traffic conditions. Spatial classification of MOBILAB measurements involved the assignment of measurement points to location bins defined by the aspect ratio of adjacent urban street canyons (USCs). Source apportionment was further carried out, by applying Positive Matrix Factorization (PMF) to particle size distribution data. Apportioned PMF factors were interpreted, by employing a two-step methodology, which involved (a) statistical association of PMF factor contributions with 12 h air-mass back-trajectories ending at the TMA during MOBILAB measurements, and (b) Multiple Linear Regression (MLR) using PMF factor contributions as the dependent variables, while relative humidity, solar radiation flux, and vehicle speed were used as the independent variables. The applied data analysis showed that low-speed cruise and high-load engine operation modes are the two dominant sources of UFPs in most of the road microenvironments in the TMA, with significant contributions from background photochemical processes during the warm period, explaining the reversed

  18. Immersion freezing in concentrated solution droplets for a variety of ice nucleating particles

    Science.gov (United States)

    Wex, Heike; Kohn, Monika; Grawe, Sarah; Hartmann, Susan; Hellner, Lisa; Herenz, Paul; Welti, Andre; Lohmann, Ulrike; Kanji, Zamin; Stratmann, Frank

    2016-04-01

    The measurement campaign LINC (Leipzig Ice Nucleation counter Comparison) was conducted in September 2015, during which ice nucleation measurements as obtained with the following instruments were compared: - LACIS (Leipzig Aerosol Cloud Interaction Simulator, see e.g. Wex et al., 2014) - PIMCA-PINC (Portable Immersion Mode Cooling Chamber together with PINC) - PINC (Portable Ice Nucleation Chamber, Chou et al., 2011) - SPIN (SPectrometer for Ice Nuclei, Droplet Measurement Technologies) While LACIS and PIMCA-PINC measured immersion freezing, PINC and SPIN varied the super-saturation during the measurements and collected data also for relative humidities below 100% RHw. A suite of different types of ice nucleating particles were examined, where particles were generated from suspensions, subsequently dried and size selected. For the following samples, data for all four instruments are available: K-feldspar, K-feldspar treated with nitric acid, Fluka-kaolinite and birch pollen. Immersion freezing measurements by LACIS and PIMCA-PINC were in excellent agreement. Respective parameterizations from these measurement were used to model the ice nucleation behavior below water vapor saturation, assuming that the process can be described as immersion freezing in concentrated solutions. This is equivalent to simply including a concentration dependent freezing point depression in the immersion freezing parameterization, as introduced for coated kaolinite particles in Wex et al. (2014). Overall, measurements performed below water vapor saturation were reproduced by the model, and it will be discussed in detail, why deviations were observed in some cases. Acknowledgement: Part of this work was funded by the DFG Research Unit FOR 1525 INUIT, grant WE 4722/1-2. Literature: Chou, C., O. Stetzer, E. Weingartner, Z. Juranyi, Z. A. Kanji, and U. Lohmann (2011), Ice nuclei properties within a Saharan dust event at the Jungfraujoch in the Swiss Alps, Atmos. Chem. Phys., 11(10), 4725

  19. A Stochastic Framework For Sediment Concentration Estimation By Accounting Random Arrival Processes Of Incoming Particles Into Receiving Waters

    Science.gov (United States)

    Tsai, C.; Hung, R. J.

    2015-12-01

    This study attempts to apply queueing theory to develop a stochastic framework that could account for the random-sized batch arrivals of incoming sediment particles into receiving waters. Sediment particles, control volume, mechanics of sediment transport (such as mechanics of suspension, deposition and resuspension) are treated as the customers, service facility and the server respectively in queueing theory. In the framework, the stochastic diffusion particle tracking model (SD-PTM) and resuspension of particles are included to simulate the random transport trajectories of suspended particles. The most distinguished characteristic of queueing theory is that customers come to the service facility in a random manner. In analogy to sediment transport, this characteristic is adopted to model the random-sized batch arrival process of sediment particles including the random occurrences and random magnitude of incoming sediment particles. The random occurrences of arrivals are simulated by Poisson process while the number of sediment particles in each arrival can be simulated by a binominal distribution. Simulations of random arrivals and random magnitude are proposed individually to compare with the random-sized batch arrival simulations. Simulation results are a probabilistic description for discrete sediment transport through ensemble statistics (i.e. ensemble means and ensemble variances) of sediment concentrations and transport rates. Results reveal the different mechanisms of incoming particles will result in differences in the ensemble variances of concentrations and transport rates under the same mean incoming rate of sediment particles.

  20. Turbulent Concentration of mm-Size Particles in the Protoplanetary Nebula: Scale-Dependent Cascades

    Science.gov (United States)

    Cuzzi, J. N.; Hartlep, T.

    2015-01-01

    The initial accretion of primitive bodies (here, asteroids in particular) from freely-floating nebula particles remains problematic. Traditional growth-by-sticking models encounter a formidable "meter-size barrier" (or even a mm-to-cm-size barrier) in turbulent nebulae, making the preconditions for so-called "streaming instabilities" difficult to achieve even for so-called "lucky" particles. Even if growth by sticking could somehow breach the meter size barrier, turbulent nebulae present further obstacles through the 1-10km size range. On the other hand, nonturbulent nebulae form large asteroids too quickly to explain long spreads in formation times, or the dearth of melted asteroids. Theoretical understanding of nebula turbulence is itself in flux; recent models of MRI (magnetically-driven) turbulence favor low-or- no-turbulence environments, but purely hydrodynamic turbulence is making a comeback, with two recently discovered mechanisms generating robust turbulence which do not rely on magnetic fields at all. An important clue regarding planetesimal formation is an apparent 100km diameter peak in the pre-depletion, pre-erosion mass distribution of asteroids; scenarios leading directly from independent nebula particulates to large objects of this size, which avoid the problematic m-km size range, could be called "leapfrog" scenarios. The leapfrog scenario we have studied in detail involves formation of dense clumps of aerodynamically selected, typically mm-size particles in turbulence, which can under certain conditions shrink inexorably on 100-1000 orbit timescales and form 10-100km diameter sandpile planetesimals. There is evidence that at least the ordinary chondrite parent bodies were initially composed entirely of a homogeneous mix of such particles. Thus, while they are arcane, turbulent concentration models acting directly on chondrule size particles are worthy of deeper study. The typical sizes of planetesimals and the rate of their formation can be

  1. Seasonal variation of atmospheric particle number concentrations, new particle formation and atmospheric oxidation capacity at the high Arctic site Villum Research Station, Station Nord

    Science.gov (United States)

    Nguyen, Quynh T.; Glasius, Marianne; Sørensen, Lise L.; Jensen, Bjarne; Skov, Henrik; Birmili, Wolfram; Wiedensohler, Alfred; Kristensson, Adam; Nøjgaard, Jacob K.; Massling, Andreas

    2016-09-01

    This work presents an analysis of the physical properties of sub-micrometer aerosol particles measured at the high Arctic site Villum Research Station, Station Nord (VRS), northeast Greenland, between July 2010 and February 2013. The study focuses on particle number concentrations, particle number size distributions and the occurrence of new particle formation (NPF) events and their seasonality in the high Arctic, where observations and characterization of such aerosol particle properties and corresponding events are rare and understanding of related processes is lacking.A clear accumulation mode was observed during the darker months from October until mid-May, which became considerably more pronounced during the prominent Arctic haze months from March to mid-May. In contrast, nucleation- and Aitken-mode particles were predominantly observed during the summer months. Analysis of wind direction and wind speed indicated possible contributions of marine sources from the easterly side of the station to the observed summertime particle number concentrations, while southwesterly to westerly winds dominated during the darker months. NPF events lasting from hours to days were mostly observed from June until August, with fewer events observed during the months with less sunlight, i.e., March, April, September and October. The results tend to indicate that ozone (O3) might be weakly anti-correlated with particle number concentrations of the nucleation-mode range (10-30 nm) in almost half of the NPF events, while no positive correlation was observed. Calculations of air mass back trajectories using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model for the NPF event days suggested that the onset or interruption of events could possibly be explained by changes in air mass origin. A map of event occurrence probability was computed, indicating that southerly air masses from over the Greenland Sea were more likely linked to those events.

  2. Beyond phthalates: Gas phase concentrations and modeled gas/particle distribution of modern plasticizers

    Energy Technology Data Exchange (ETDEWEB)

    Schossler, Patricia [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54E, D-38108 Braunschweig (Germany); Institute of Environmental and Sustainable Chemistry, Technische Universitaet Braunschweig, Hagenring 30, D-38106 Braunschweig (Germany); Schripp, Tobias, E-mail: tobias.schripp@wki.fraunhofer.de [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54E, D-38108 Braunschweig (Germany); Salthammer, Tunga [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54E, D-38108 Braunschweig (Germany); Bahadir, Muefit [Institute of Environmental and Sustainable Chemistry, Technische Universitaet Braunschweig, Hagenring 30, D-38106 Braunschweig (Germany)

    2011-09-01

    The ongoing health debate about polymer plasticizers based on the esters of phthalic acid, especially di(2-ethylhexyl) phthalate (DEHP), has caused a trend towards using phthalates of lower volatility such as diisononyl phthalate (DINP) and towards other acid esters, such as adipates, terephthalates, citrates, etc. Probably the most important of these so-called 'alternative' plasticizers is diisononyl cyclohexane-1,2-dicarboxylate (DINCH). In the indoor environment, the continuously growing market share of this compound since its launch in 2002 is inter alia apparent from the increasing concentration of DINCH in settled house dust. From the epidemiological point of view there is considerable interest in identifying how semi-volatile organic compounds (SVOCs) distribute in the indoor environment, especially in air, airborne particles and sedimented house dust. This, however, requires reliable experimental concentration data for the different media and good measurements or estimates of their physical and chemical properties. This paper reports on air concentrations for DINP, DINCH, diisobutyl phthalate (DIBP), diisobutyl adipate (DIBA), diisobutyl succinate (DIBS) and diisobutyl glutarate (DIBG) from emission studies in the Field and Laboratory Emission Cell (FLEC). For DINP and DINCH it took about 50 days to reach the steady-state value: for four months no decay in the concentration could be observed. Moreover, vapor pressures p{sub 0} and octanol-air partitioning coefficients K{sub OA} were obtained for 37 phthalate and non-phthalate plasticizers from two different algorithms: EPI Suite and SPARC. It is shown that calculated gas/particle partition coefficients K{sub p} and fractions can widely differ due to the uncertainty in the predicted p{sub 0} and K{sub OA} values. For most of the investigated compounds reliable experimental vapor pressures are not available. Rough estimates can be obtained from the measured emission rate of the pure compound in a

  3. Concentrated ambient ultrafine particle exposure induces cardiac change in young healthy volunteers

    Science.gov (United States)

    Exposure to ambient ultrafine particles has been associated with cardiopulmonary toxicity and mortality. Adverse effects specifically linked to ultrafine particles include loss of sympathovagal balance and altered hemostasis. To characterize the effects of ultrafine particles in ...

  4. The effects of vehicle emissions and nucleation events on vertical particle concentration profiles around urban office buildings

    Directory of Open Access Journals (Sweden)

    T. N. Quang

    2012-01-01

    Full Text Available Despite its role in determining both indoor and outdoor human exposure to anthropogenic particles, there is limited information describing vertical profiles of particle concentrations in urban environments, especially for ultrafine particles. Furthermore, the results of the few studies performed have been inconsistent. As such this study aimed to assess the influence of vehicle emissions and nucleation formation on particle concentrations (PN and PM2.5 at different heights around three urban office buildings located next to busy roads in Brisbane, Australia, and place these results in the broader context of the existing literature. Two sets of instruments were used to simultaneously measure PN size distribution, PN and PM2.5 concentrations, respectively, for up to three weeks each at three office buildings.

    The results showed that both PN and PM2.5 concentrations around building envelope were influenced by vehicle emissions and new particle formation, and that they exhibited variability across the three different office buildings. During the nucleation event, PN concentrations increased (21–46%, while PM2.5 concentrations decreased (36–52% with height at all three buildings.

    This study has shown an underappreciated role of nucleation in producing particles that can affect large numbers of people, due to the high density and occupancy of urban office buildings and the fact that the vast majority of people's time is spent indoors. These findings highlight important new information related to the previously overlooked role of particle formation in the urban atmosphere and its potential effects on selection of air intake locations and appropriate filter types when designing or upgrading mechanical ventilation systems in urban office buildings. The results also serve to better define particle behaviour and variability around building envelopes, which has implications for studies of

  5. Particle characteristics and rheological constitutive relations of high concentration red mud

    Institute of Scientific and Technical Information of China (English)

    WANG Xing; QU Yuan-yuan; HU Wei-wei; CHEN Jie; ZHAO Xue-yi; WU Miao

    2008-01-01

    Red mud has relatively small solid particles (d50=13.02 μm) and will flow in paste form under high pressure during pipeline transport. Red mud belongs to a two-phase flow of materials with high viscosity and a high concentration of non-sedimentation, homogeneous solid-liquids. It is difficult to test its rheological properties under atmospheric pressure. Measurements such as rotational viscometry can not reflect the real state of the material when it is flowing in a pipe. Tested rheological parameters are somewhat higher than the actual values. In our investigation, grain shape, distinctive modality and grain size distribution of red mud were tested. Based on the principle of tube measurement, rheological experiments on red mud at different concentrations were carried out by using our independently developed tube-type pressure rheology test facility, and obtained constitutive equations. We conclude that red mud behaves as non-Newtonian pseudo-plastic fluid in pipe flows. Its consistency and power-law indices vary considerably with different concentrations.

  6. Effect of PCSK9 Inhibition by Alirocumab on Lipoprotein Particle Concentrations Determined by Nuclear Magnetic Resonance Spectroscopy.

    Science.gov (United States)

    Koren, Michael J; Kereiakes, Dean; Pourfarzib, Ray; Winegar, Deborah; Banerjee, Poulabi; Hamon, Sara; Hanotin, Corinne; McKenney, James M

    2015-11-19

    In patients with discordance between low-density lipoprotein (LDL) cholesterol and LDL particle (LDL-P) concentrations, cardiovascular risk more closely correlates with LDL-P. We investigated the effect of alirocumab, a fully human monoclonal antibody to proprotein convertase subtilisin/kexin type 9, on lipoprotein particle concentration and size in hypercholesterolemic patients, using nuclear magnetic resonance spectroscopy. Plasma samples were collected from patients receiving alirocumab 150 mg every 2 weeks (n=26) or placebo (n=31) during a phase II, double-blind, placebo-controlled trial in patients (LDL cholesterol ≥100 mg/dL) on a stable atorvastatin dose. In this post hoc analysis, percentage change in concentrations of LDL-P, very-low-density lipoprotein particles, and high-density lipoprotein particles from baseline to week 12 was determined by nuclear magnetic resonance. Alirocumab significantly reduced mean concentrations of total LDL-P (-63.3% versus -1.0% with placebo) and large (-71.3% versus -21.8%) and small (-54.0% versus +17.8%) LDL-P subfractions and total very-low-density lipoprotein particle concentrations (-36.4% versus +33.4%; all Plipoprotein particles increased with alirocumab (+11.2% versus +1.4% with placebo; Plipoprotein particles (2.8%) with alirocumab. LDL-P size remained relatively unchanged in both groups; however, very-low-density and high-density lipoprotein particle sizes increased to a significantly greater extent with alirocumab. Alirocumab significantly reduced LDL-C and LDL-P concentrations in hypercholesterolemic patients receiving stable atorvastatin therapy. These findings may be of particular relevance to patients with discordant LDL-C and LDL-P concentrations. URL: https://clinicaltrials.gov. Unique identifier: NCT01288443. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  7. Sensitive Detection and Identification of Isovanillin Aerosol Particles at the pg/cm3 Mass Concentration Level using Raman Spectroscopy

    Science.gov (United States)

    2017-04-24

    Particles at the pg/cm3 Mass Concentration Level Using Raman Spectroscopy* R. L. Aggarwal1, S. Di Cecca, L. W. Farrar, Shabshelowitz, A...and identification of isovanillin (C8H8O3, CAS No. 621‐59‐0; Molecular mass 152.15; Density 1.41) aerosol particles of mass concentration MC of 1.8...optical particle sizer. (iv) Aerosol flow cell, fabricated by the U.S. Army Edgewood Chemical and Biological Center (ECBC), with two

  8. The effect of concentration of glycerol and electric current on the morphology and particle size of electrodeposited cadmium powder

    Directory of Open Access Journals (Sweden)

    S. G. Viswanath

    2013-06-01

    Full Text Available Cadmium powder was obtained by electrodeposition of cadmium from glycerol and sulphuric acid. The morphology and particle size of these powders were studied. Broken dendrites, intermingled with spongy and irregular particles were observed in the powder. Around 60% of particles were below 100 µm. XRD studies showed that particles with sizes between 212.2 and 303.2 nm were present in the powder. The apparent density of cadmium powder decreased with increase in concentration of glycerol. The stability of the powder and current efficiency were also studied

  9. International Airport Impacts to Air Quality: Size and Related Properties of Large Increases in Ultrafine Particle Number Concentrations.

    Science.gov (United States)

    Hudda, N; Fruin, S A

    2016-04-05

    We measured particle size distributions and spatial patterns of particle number (PN) and particle surface area concentrations downwind from the Los Angeles International Airport (LAX) where large increases (over local background) in PN concentrations routinely extended 18 km downwind. These elevations were mostly comprised of ultrafine particles smaller than 40 nm. For a given downwind distance, the greatest increases in PN concentrations, along with the smallest mean sizes, were detected at locations under the landing jet trajectories. The smaller size of particles in the impacted area, as compared to the ambient urban aerosol, increased calculated lung deposition fractions to 0.7-0.8 from 0.5-0.7. A diffusion charging instrument (DiSCMini), that simulates alveolar lung deposition, measured a fivefold increase in alveolar-lung deposited surface area concentrations 2-3 km downwind from the airport (over local background), decreasing steadily to a twofold increase 18 km downwind. These ratios (elevated lung-deposited surface area over background) were lower than the corresponding ratios for elevated PN concentrations, which decreased from tenfold to twofold over the same distance, but the spatial patterns of elevated concentrations were similar. It appears that PN concentration can serve as a nonlinear proxy for lung deposited surface area downwind of major airports.

  10. Concentrations and fluxes of aerosol particles during the LAPBIAT measurement campaign in Värriö field station

    Directory of Open Access Journals (Sweden)

    T. M. Ruuskanen

    2007-01-01

    Full Text Available The LAPBIAT measurement campaign took place in the SMEAR I measurement station located in Eastern Lapland in the spring of 2003 between 26 April and 11 May. In this paper we describe the measurement campaign, concentrations and fluxes of aerosol particles, air ions and trace gases, paying special attention to an aerosol particle formation event broken by a polluted air mass approaching from industrial areas of Kola Peninsula, Russia. Aerosol particle number flux measurements show strong downward fluxes during that time. Concentrations of coarse aerosol particles were high for 1–2 days before the nucleation event (i.e. 28–29 April, very low immediately before and during the observed aerosol particle formation event (30 April and increased moderately from the moment of sudden break of the event. In general particle deposition measurements based on snow samples show the same changes. Measurements of the mobility distribution of air ions showed elevated concentrations of intermediate air ions during the particle formation event. We estimated the growth rates in the nucleation mode size range. For particles <10 nm, the growth rate increases with size on 30 April. Dispersion modelling made with model SILAM support the conclusion that the nucleation event was interrupted by an outbreak of sulphate-rich air mass in the evening of 30 April that originated from the industry at Kola Peninsula, Russia. The results of this campaign highlight the need for detailed research in atmospheric transport of air constituents for understanding the aerosol dynamics.

  11. Adsorption of zinc on manganite (γ-MnOOH):particle concentration effect and adsorption reversibility

    Institute of Scientific and Technical Information of China (English)

    QIN Yan-wen; PAN Gang; ZHANG Ming-ming; LI Xian-liang

    2004-01-01

    The adsorption and desorption processes of Zn(Ⅱ) on γ-MnOOH as a function of particle concentrations (Cp) were studied. An obvious Cp effect was observed in this adsorption system. The degree of adsorption hysteresis increased greatly with the increasing of Cp, indicating that the extent of the real metastable-equilibrium states deviating from the ideal equilibrium state was enhanced with the increasing of Cp. The Cp-reversibility relationship confirmed the metastable-equilibrium adsorption (MEA) inequality (Pan, 1998a), which was the core formulation of the MEA theory. Because the MEA inequality was based on the basic hypothesis of MEA theory that adsorption density Г is not a state variable, the Cp-reversibility relationship gave indirect evidence to the basic hypothesis of MEA theory.

  12. Impurity identifications, concentrations and particle fluxes from spectral measurements of the EXTRAP T2R plasma

    Science.gov (United States)

    Menmuir, S.; Kuldkepp, M.; Rachlew, E.

    2006-10-01

    An absolute intensity calibrated 0.5 m spectrometer with optical multi-channel analyser detector was used to observe the visible-UV radiation from the plasma in the EXTRAP T2R reversed field pinch experiment. Spectral lines were identified indicating the presence of oxygen, chromium, iron and molybdenum impurities in the hydrogen plasma. Certain regions of interest were examined in more detail and at different times in the plasma discharge. Impurity concentration calculations were made using the absolute intensities of lines of OIV and OV measured at 1-2 ms into the discharge generating estimates of the order of 0.2% of ne in the central region rising to 0.7% of ne at greater radii for OIV and 0.3% rising to 0.6% for OV. Edge electron temperatures of 0.5-5 eV at electron densities of 5-10×1011 cm-3 were calculated from the measured relative intensities of hydrogen Balmer lines. The absolute intensities of hydrogen lines and of multiplets of neutral chromium and molybdenum were used to determine particle fluxes (at 4-5 ms into the plasma) of the order 1×1016, 7×1013 and 3×1013 particles cm-2 s-1, respectively.

  13. Source appointment of fine particle number and volume concentration during severe haze pollution in Beijing in January 2013.

    Science.gov (United States)

    Liu, Zirui; Wang, Yuesi; Hu, Bo; Ji, Dongsheng; Zhang, Junke; Wu, Fangkun; Wan, Xin; Wang, Yonghong

    2016-04-01

    Extreme haze episodes repeatedly shrouded Beijing during the winter of 2012-2013, causing major environmental and health problems. To better understand these extreme events, particle number size distribution (PNSD) and particle chemical composition (PCC) data collected in an intensive winter campaign in an urban site of Beijing were used to investigate the sources of ambient fine particles. Positive matrix factorization (PMF) analysis resolved a total of eight factors: two traffic factors, combustion factors, secondary aerosol, two accumulation mode aerosol factors, road dust, and long-range transported (LRT) dust. Traffic emissions (54%) and combustion aerosol (27%) were found to be the most important sources for particle number concentration, whereas combustion aerosol (33%) and accumulation mode aerosol (37%) dominated particle volume concentrations. Chemical compositions and sources of fine particles changed dynamically in the haze episodes. An enhanced role of secondary inorganic species was observed in the formation of haze pollution. Regional transport played an important role for high particles, contribution of which was on average up to 24-49% during the haze episodes. Secondary aerosols from urban background presented the largest contributions (45%) for the rapid increase of fine particles in the severest haze episode. In addition, the invasion of LRT dust aerosols further elevated the fine particles during the extreme haze episode. Our results showed a clear impact of regional transport on the local air pollution, suggesting the importance of regional-scale emission control measures in the local air quality management of Beijing.

  14. Correlations between urban atmospheric light extinction coefficients and fine particle mass concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Trier, A.; Cabrini, N.; Ferrer, J. [Facultad de Ciencia, Universidad de Santiago de Chile, Santiago 2 (Chile); Olaeta, I. [SESMA, Santiago 1 (Chile)

    1997-07-01

    Total horizontal atmospheric light extinction coefficients as well as particle mass concentrations have been measured in downtown areas of Santiago de Chile, a heavily polluted city. Measurement campaigns were carried out in 1994 in 1995. Extinction measurements were made by a telephotometric technique in four wavelength bands; oscillating mass balance type instruments were used to measure PM2.5 and PM10 mass concentrations. The latter type instrument had not been available heretofore. The extensive continuous PM2.5 measurements are the first for this city. Strong and highly significant statistical correlations were found between extinction coefficients and mass concentrations, especially with the fine respirable or PM2.5 mass concentrations. Angstrom exponents and, in one case, mass extinction coefficients have been estimated. [Spanish] Se ha medido coeficientes atmosfericos totales horizontales de extincion de luz asi como concentraciones de masa de particulas atmosfericas en zonas centricas de Santiago de Chile, una ciudad altamente contaminada. Las campanas de medicion se han hecho en 1994 y en 1995. Las mediciones de extincion se han hecho por un metodo telefotometrico en cuatro bandas espectrales; las concentraciones de masa PM2.5 y PM10 se han medido con instrumentos del tipo de balanzas de masa oscilantes. Tales instrumentos no han estado disponibles durante trabajos anteriores. Las extensas mediciones continuas de concentraciones de masa PM2.5 son las primeras para Santiago de Chile. Se han encontrado fuertes correlaciones estadisticas, altamente significativas, entre coeficientes de extincion y concentraciones de masa, especialmente las concentraciones de particulas finas respirables PM2.5. Se han estimado tambien exponentes de Angstrom y, en un caso, coeficientes masicos de extincion.

  15. Highly Localized Acoustic Streaming and Size-Selective Submicrometer Particle Concentration Using High Frequency Microscale Focused Acoustic Fields.

    Science.gov (United States)

    Collins, David J; Ma, Zhichao; Ai, Ye

    2016-05-17

    Concentration and separation of particles and biological specimens are fundamental functions of micro/nanofluidic systems. Acoustic streaming is an effective and biocompatible way to create rapid microscale fluid motion and induce particle capture, though the >100 MHz frequencies required to directly generate acoustic body forces on the microscale have traditionally been difficult to generate and localize in a way that is amenable to efficient generation of streaming. Moreover, acoustic, hydrodynamic, and electrical forces as typically applied have difficulty manipulating specimens in the submicrometer regime. In this work, we introduce highly focused traveling surface acoustic waves (SAW) at high frequencies between 193 and 636 MHz for efficient and highly localized production of acoustic streaming vortices on microfluidic length scales. Concentration occurs via a novel mechanism, whereby the combined acoustic radiation and streaming field results in size-selective aggregation in fluid streamlines in the vicinity of a high-amplitude acoustic beam, as opposed to previous acoustic radiation induced particle concentration where objects typically migrate toward minimum pressure locations. Though the acoustic streaming is induced by a traveling wave, we are able to manipulate particles an order of magnitude smaller than possible using the traveling wave force alone. We experimentally and theoretically examine the range of particle sizes that can be captured in fluid streamlines using this technique, with rapid particle concentration demonstrated down to 300 nm diameters. We also demonstrate that locations of trapping and concentration are size-dependent, which is attributed to the combined effects of the acoustic streaming and acoustic forces.

  16. Fluorescent biological aerosol particle concentrations and size distributions measured with an Ultraviolet Aerodynamic Particle Sizer (UV-APS) in Central Europe

    Science.gov (United States)

    Huffman, J. A.; Treutlein, B.; Pöschl, U.

    2010-04-01

    Primary Biological Aerosol Particles (PBAPs), including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany we used an Ultraviolet Aerodynamic Particle Sizer (UV-APS) to measure Fluorescent Biological Aerosol Particles (FBAPs), which provide an estimate of viable bioaerosol particles and can be regarded as an approximate lower limit for the actual abundance of PBAPs. Fluorescence of non-biological aerosol components are likely to influence the measurement results obtained for fine particles (particles (1-20 μm). Averaged over the four-month measurement period (August-December 2006), the mean number concentration of coarse FBAPs was ~3×10-2 cm-3, corresponding to ~4% of total coarse particle number. The mean mass concentration of FBAPs was ~1μg m-3, corresponding to ~20% of total coarse particle mass. The FBAP number size distributions exhibited alternating patterns with peaks at various diameters. A pronounced peak at ~3 μm was essentially always observed and can be described by the following campaign-average lognormal fit parameters: geometric mean diameter 3.2 μm, geometric standard deviation 1.3, number concentration 1.6×10-2 cm-3. This peak is likely due to fungal spores or agglomerated bacteria, and it exhibited a pronounced diel cycle (24-h) with maximum intensity during early/mid-morning. FBAP peaks around ~1.5 μm, ~5 μm, and ~13 μm were also observed, but less pronounced and less frequent. These may be single bacterial cells, larger fungal spores, and pollen grains, respectively. The observed number concentrations and characteristic sizes of FBAPs are consistent with microscopic, biological and chemical analyses of PBAPs in aerosol

  17. Isoprene in poplar emissions: effects on new particle formation and OH concentrations

    Directory of Open Access Journals (Sweden)

    A. Kiendler-Scharr

    2012-01-01

    Full Text Available Stress-induced volatile organic compound (VOC emissions from transgenic Grey poplar modified in isoprene emission potential were used for the investigation of photochemical secondary organic aerosol (SOA formation. In poplar, acute ozone stress induces the emission of a wide array of VOCs dominated by sesquiterpenes and aromatic VOCs. Constitutive light-dependent emission of isoprene ranged between 66 nmol m−2 s−1 in non-transgenic controls (wild type WT and nearly zero (<0.5 nmol m−2 s−1 in isoprene emission-repressed plants (line RA22, respectively. Nucleation rates of up to 3600 cm−3 s−1 were observed in our experiments. In the presence of isoprene new particle formation was suppressed compared to non-isoprene containing VOC mixtures. Compared to isoprene/monoterpene systems emitted from other plants the suppression of nucleation by isoprene was less effective for the VOC mixture emitted from stressed poplar. This is explained by the observed high efficiency of new particle formation for emissions from stressed poplar. Direct measurements of OH in the reaction chamber revealed that the steady state concentration of OH is lower in the presence of isoprene than in the absence of isoprene, supporting the hypothesis that isoprenes' suppressing effect on nucleation is related to radical chemistry. In order to test whether isoprene contributes to SOA mass formation, fully deuterated isoprene (C5D8 was added to the stress-induced emission profile of an isoprene free poplar mutant. Mass spectral analysis showed that, despite the isoprene-induced suppression of particle formation, fractions of deuterated isoprene were incorporated into the SOA. A fractional mass yield of 2.3% of isoprene was observed. Future emission changes due to land use and climate change may therefore affect both gas phase oxidation capacity and new particle number formation.

  18. Isoprene in poplar emissions: effects on new particle formation and OH concentrations

    Directory of Open Access Journals (Sweden)

    A. Kiendler-Scharr

    2011-08-01

    Full Text Available Stress-induced volatile organic compound (VOC emissions from transgenic Grey poplar, modified in isoprene emission potential were used for the investigation of photochemical secondary organic aerosol (SOA formation. Nucleation rates of up to 3600 cm−3 s−1 were observed in our experiments. In poplar, acute ozone stress induces the emission of a wide array of VOCs dominated by sesquiterpenes and aromatic VOCs. Constitutive light-dependent emission of isoprene ranged between 66 nmol m−2 s−1 in non-transgenic controls (wild type WT and nearly zero (<0.5 nmol m−2 s−1 in isoprene emission-repressed lines (line RA22, respectively. In the presence of isoprene new particle formation was suppressed compared to non-isoprene containing VOC mixtures. Compared to isoprene/monoterpene systems emitted from other plants the suppression of nucleation by isoprene was less effective for the VOC mixture emitted from stressed poplar. This is explained by the observed high efficiency of new particle formation for emissions from stressed poplar. Direct measurements of OH in the reaction chamber revealed that the steady state concentration of OH is lower in the presence of isoprene than in the absence of isoprene, supporting the hypothesis that isoprenes' suppressing effect on nucleation is related to radical chemistry. In order to test whether isoprene contributes to SOA mass formation, fully deuterated isoprene (C5D8 was added to the stress-induced emission profile of an isoprene free poplar mutant. Mass spectral analysis showed that, despite the isoprene-induced suppression of particle formation, fractions of deuterated isoprene were incorporated into the SOA. A fractional mass yield of 2.3 % of isoprene was observed. Future emission changes due to land use and climate change may therefore affect both gas phase oxidation capacity and new particle number formation.

  19. Suspended sediment concentration and particle size distribution, and their relationship with heavy metal content

    Indian Academy of Sciences (India)

    S H R Sadeghi; M Kiani Harchegani; H A Younesi

    2012-02-01

    This paper aims at assessing the feasibility of suspended sediment concentration (SSC) estimation by using predictor variables of heavy metal concentration (HMC, viz., iron, chromium, zinc and nickel) transported in solution and solid. The study was conducted in the Research and Educational Forest Watershed of the Tarbiat Modares University (Kojour) which comprises an area of ca. 50000 ha. For this study, suspended sediment samples were collected from the left bank of the Kojour River twice a week, as well as during runoff events from November 2007 to June 2008. The samples were then prepared through direct digestion and finally analyzed by atomic absorption spectrophotometry (AAS). The relationship between SSC and particle size distribution (PSD) were correlated with HMC by using bivariate and multivariate regression models. Proposed models were then selected based on statistical criteria. The results showed high correlation between dissolved and particulate chromium content with efficiency coefficients beyond 77% ( > 0.001). However, a lower relationship was found between SSC and nickel content. From these results, it is clearly shown that the HMC can practically be estimated by SSC in watersheds with different accuracy and vice versa. It is also understood that heavy metal pollution can be easily managed by controlling SSC.

  20. Understanding Ice Supersaturation, Particle Growth, and Number Concentration in Cirrus Clouds

    Science.gov (United States)

    Comstock, Jennifer M.; Lin, Ruei-Fong; Starr, David O'C.; Yang, Ping

    2008-01-01

    Many factors control the ice supersaturation and microphysical properties in cirrus clouds. We explore the effects of dynamic forcing, ice nucleation mechanisms, and ice crystal growth rate on the evolution and distribution of water vapor and cloud properties in nighttime cirrus clouds using a one-dimensional cloud model with bin microphysics and remote sensing measurements obtained at the Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility located near Lamont, OK. We forced the model using both large-scale vertical ascent and, for the first time, mean mesoscale velocity derived from radar Doppler velocity measurements. Both heterogeneous and homogeneous nucleation processes are explored, where a classical theory heterogeneous scheme is compared with empirical representations. We evaluated model simulations by examining both bulk cloud properties and distributions of measured radar reflectivity, lidar extinction, and water vapor profiles, as well as retrieved cloud microphysical properties. Our results suggest that mesoscale variability is the primary mechanism needed to reproduce observed quantities. Model sensitivity to the ice growth rate is also investigated. The most realistic simulations as compared with observations are forced using mesoscale waves, include fast ice crystal growth, and initiate ice by either homogeneous or heterogeneous nucleation. Simulated ice crystal number concentrations (tens to hundreds particles per liter) are typically two orders of magnitude smaller than previously published results based on aircraft measurements in cirrus clouds, although higher concentrations are possible in isolated pockets within the nucleation zone.

  1. Particle Concentration and Yield Stress of Biomass Slurries During Enzymatic Hydrolysis at High-Solids Loadings

    Energy Technology Data Exchange (ETDEWEB)

    Roche, C. M.; Dibble, C. J.; Knutsen, J. S.; Stickel, J. J.; Liberatore, M. W.

    2009-01-01

    Effective and efficient breakdown of lignocellulosic biomass remains a primary barrier for its use as a feedstock for renewable transportation fuels. A more detailed understanding of the material properties of biomass slurries during conversion is needed to design cost-effective conversion processes. A series of enzymatic saccharification experiments were performed with dilute acid pretreated corn stover at initial insoluble solids loadings of 20% by mass, during which the concentration of particulate solids and the rheological property yield stress ({tau}{sub y}) of the slurries were measured. The saccharified stover liquefies to the point of being pourable ({tau}{sub y} {le} 10 Pa) at a total biomass conversion of about 40%, after roughly 2 days of saccharification for a moderate loading of enzyme. Mass balance and semi-empirical relationships are developed to connect the progress of enzymatic hydrolysis with particle concentration and yield stress. The experimental data show good agreement with the proposed relationships. The predictive models developed here are based on established physical principles and should be applicable to the saccharification of other biomass systems. The concepts presented, especially the ability to predict yield stress from extent of conversion, will be helpful in the design and optimization of enzymatic hydrolysis processes that operate at high-solids loadings.

  2. Indoor-to-outdoor particle concentration ratio model for human exposure analysis

    Science.gov (United States)

    Lee, Jae Young; Ryu, Sung Hee; Lee, Gwangjae; Bae, Gwi-Nam

    2016-02-01

    This study presents an indoor-to-outdoor particle concentration ratio (IOR) model for improved estimates of indoor exposure levels. This model is useful in epidemiological studies with large population, because sampling indoor pollutants in all participants' house is often necessary but impractical. As a part of a study examining the association between air pollutants and atopic dermatitis in children, 16 parents agreed to measure the indoor and outdoor PM10 and PM2.5 concentrations at their homes for 48 h. Correlation analysis and multi-step multivariate linear regression analysis was performed to develop the IOR model. Temperature and floor level were found to be powerful predictors of the IOR. Despite the simplicity of the model, it demonstrated high accuracy in terms of the root mean square error (RMSE). Especially for long-term IOR estimations, the RMSE was as low as 0.064 and 0.063 for PM10 and PM2.5, respectively. When using a prediction model in an epidemiological study, understanding the consequence of the modeling error and justifying the use of the model is very important. In the last section, this paper discussed the impact of the modeling error and developed a novel methodology to justify the use of the model.

  3. Aircraft observations and model simulations of concentration and particle size distribution in the Eyjafjallajökull volcanic ash cloud

    Science.gov (United States)

    Dacre, H. F.; Grant, A. L. M.; Johnson, B. T.

    2013-02-01

    The Eyjafjallajökull volcano in Iceland emitted a cloud of ash into the atmosphere during April and May 2010. Over the UK the ash cloud was observed by the FAAM BAe-146 Atmospheric Research Aircraft which was equipped with in-situ probes measuring the concentration of volcanic ash carried by particles of varying sizes. The UK Met Office Numerical Atmospheric-dispersion Modelling Environment (NAME) has been used to simulate the evolution of the ash cloud emitted by the Eyjafjallajökull volcano during the period 4-18 May 2010. In the NAME simulations the processes controlling the evolution of the concentration and particle size distribution include sedimentation and deposition of particles, horizontal dispersion and vertical wind shear. For travel times between 24 and 72 h, a 1/t relationship describes the evolution of the concentration at the centre of the ash cloud and the particle size distribution remains fairly constant. Although NAME does not represent the effects of microphysical processes, it can capture the observed decrease in concentration with travel time in this period. This suggests that, for this eruption, microphysical processes play a small role in determining the evolution of the distal ash cloud. Quantitative comparison with observations shows that NAME can simulate the observed column-integrated mass if around 4% of the total emitted mass is assumed to be transported as far as the UK by small particles (< 30 μm diameter). NAME can also simulate the observed particle size distribution if a distal particle size distribution that contains a large fraction of < 10 μm diameter particles is used, consistent with the idea that phraetomagmatic volcanoes, such as Eyjafjallajökull, emit very fine particles.

  4. Aircraft observations and model simulations of concentration and particle size distribution in the Eyjafjallajökull volcanic ash cloud

    Directory of Open Access Journals (Sweden)

    H. F. Dacre

    2013-02-01

    Full Text Available The Eyjafjallajökull volcano in Iceland emitted a cloud of ash into the atmosphere during April and May 2010. Over the UK the ash cloud was observed by the FAAM BAe-146 Atmospheric Research Aircraft which was equipped with in-situ probes measuring the concentration of volcanic ash carried by particles of varying sizes. The UK Met Office Numerical Atmospheric-dispersion Modelling Environment (NAME has been used to simulate the evolution of the ash cloud emitted by the Eyjafjallajökull volcano during the period 4–18 May 2010. In the NAME simulations the processes controlling the evolution of the concentration and particle size distribution include sedimentation and deposition of particles, horizontal dispersion and vertical wind shear. For travel times between 24 and 72 h, a 1/t relationship describes the evolution of the concentration at the centre of the ash cloud and the particle size distribution remains fairly constant. Although NAME does not represent the effects of microphysical processes, it can capture the observed decrease in concentration with travel time in this period. This suggests that, for this eruption, microphysical processes play a small role in determining the evolution of the distal ash cloud. Quantitative comparison with observations shows that NAME can simulate the observed column-integrated mass if around 4% of the total emitted mass is assumed to be transported as far as the UK by small particles (< 30 μm diameter. NAME can also simulate the observed particle size distribution if a distal particle size distribution that contains a large fraction of < 10 μm diameter particles is used, consistent with the idea that phraetomagmatic volcanoes, such as Eyjafjallajökull, emit very fine particles.

  5. Aircraft observations and model simulations of concentration and particle size distribution in the Eyjafjallajökull volcanic ash cloud

    Directory of Open Access Journals (Sweden)

    H. F. Dacre

    2012-09-01

    Full Text Available The Eyjafjallajökull volcano in Iceland emitted a cloud of ash into the atmosphere during April and May 2010. Over the UK the ash cloud was observed by the FAAM BAe-146 Atmospheric Research Aircraft which was equipped with in-situ probes measuring the concentration of volcanic ash carried by particles of varying sizes. The UK Met Office Numerical Atmospheric-dispersion Modelling Environment (NAME has been used to simulate the evolution of the ash cloud emitted by the Eyjafjallajökull volcano during the period 4–18 May 2010. In the NAME simulations the processes controlling the evolution of the concentration and particle size distribution include sedimentation and deposition of particles, horizontal dispersion and vertical wind shear. For travel times between 24 and 72 h a 1/t relationship describes the evolution of the concentration at the centre of the ash cloud and the particle size distribution remains fairly constant. Although NAME does not represent the effects of microphysical processes it can capture the observed decrease in concentration with travel time in this period. This suggests that, for this eruption, microphysical processes play a small role in determining the evolution of the distal ash cloud. Quantitative comparison with observations shows that NAME can simulate the observed column integrated mass if around 4% of the total emitted mass is assumed to be transported as far as the UK by small (<30 m diameter particles. NAME can also simulate the observed particle size distribution if a distal particle size distribution that contains a large fraction of <10 m diameter particles is used, consistent with the idea that phraetomagmatic volcanoes, such as Eyjafjallajökull, emit very fine particles.

  6. Long-term aerosol measurements in Gran Canaria, Canary Islands: Particle concentration, sources and elemental composition

    Science.gov (United States)

    Gelado-Caballero, MaríA. D.; López-GarcíA, Patricia; Prieto, Sandra; Patey, Matthew D.; Collado, Cayetano; HéRnáNdez-Brito, José J.

    2012-02-01

    There are very few sets of long-term measurements of aerosol concentrations over the North Atlantic Ocean, yet such data is invaluable in quantifying atmospheric dust inputs to this ocean region. We present an 8-year record of total suspended particles (TSP) collected at three stations on Gran Canaria Island, Spain (Taliarte at sea level, Tafira 269 m above sea level (a.s.l.) and Pico de la Gorra 1930 m a.s.l.). Using wet and dry deposition measurements, the mean dust flux was calculated at 42.3 mg m-2 d-1. Air mass back trajectories (HYSPLIT, NOAA) suggested that the Sahara desert is the major source of African dust (dominant during 32-50% of days), while the Sahel desert was the major source only 2-10% of the time (maximum in summer). Elemental composition ratios of African samples indicate that, despite the homogeneity of the dust in collected samples, some signatures of the bedrocks can still be detected. Differences were found for the Sahel, Central Sahara and North of Sahara regions in Ti/Al, Mg/Al and Ca/Al ratios, respectively. Elements often associated with pollution (Pb, Cd, Ni, Zn) appeared to share a common origin, while Cu may have a predominantly local source, as suggested by a decrease in the enrichment factor (EF) of Cu during dust events. The inter-annual variability of dust concentrations is investigated in this work. During winter, African dust concentration measurements at the Pico de la Gorra station were found to correlate with the North Atlantic Oscillation (NAO) index.

  7. Characteristics of Lipoprotein Peak x Eluted from a Column with the Eluent of High-magnesium Ion Concentration in Lipoprotein Analysis Using the Cation-exchange Chromatography

    Directory of Open Access Journals (Sweden)

    Yuji Hirowatari

    2005-01-01

    Full Text Available The new lipoprotein analysis method using a cation-exchange chromatography, which contains a sulfopropyl-ligand column and two magnesium ion-containing eluents was previously reported. This method can separate serum lipoproteins on the column gel with a magnesium ion concentration gradient and high-density lipoprotein (HDL, low-density lipoprotein (LDL, very-low-density lipoprotein (VLDL and an unspecified lipoprotein peak are eluted in order from the column. We have now characterized the unspecified lipoproteins, designated peak x, which is last eluted from the column with the eluent of high-magnesium ion concentration. The peak x was small size chylomicron fraction with a part of VLDL. Furthermore, the cholesterol values in the peak x were significantly correlated with remnant-like particle (RLP-cholesterol values. The peak x separated from a hyperlipidemic patient included apolipoprotein B-100, B-48, E, A-1 and Cs (C-I, C-II, C-III and its composition of free cholesterol, cholesteryl esters, triglyceride (TG and phospholipids in total lipids were 6, 15, 66 and 13%, respectively. These results suggest that a major part of the lipoprotein peak X may be composed of remnants of chylomicron and VLDL, but it remains to be elucidated.

  8. Particle concentration effect in adsorption/desorption of Zn(II) on anatase type nano TiO2

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Adsorption/desorption in a new Zn(II)-TiO2 adsorption system was investigated at different particle concentrations (Cp). TEM, SEM and XRD analyses revealed that the TiO2 particles were an aggregation of nano-sized (approximately 10 nm) pure anatase-type TiO2. Adsorption experiments were carried out with particle concentrations of 100, 400 and 1000 mg/L, and their adsorption isotherms were found to decline successively, showing an obvious Cp effect. Desorption experiments indicated that adsorption in this system was irreversible, and the irreversibility increased with increasing Cp. These phenomena could be explained by the MEA (metastable equilibrium adsorption) theory and the Cp effect could be modeled well with an MEA-Freundlich-type Cp effect isotherm equation. This study may help understand environmental behavior of contaminants on ultrafine natural particles.

  9. Achieving secondary prevention low-density lipoprotein particle concentration goals using lipoprotein cholesterol-based data.

    Directory of Open Access Journals (Sweden)

    Simon C Mathews

    Full Text Available BACKGROUND: Epidemiologic studies suggest that LDL particle concentration (LDL-P may remain elevated at guideline recommended LDL cholesterol goals, representing a source of residual risk. We examined the following seven separate lipid parameters in achieving the LDL-P goal of <1000 nmol/L goal for very high risk secondary prevention: total cholesterol to HDL cholesterol ratio, TC/HDL, <3; a composite of ATP-III very high risk targets, LDL-C<70 mg/dL, non-HDL-C<100 mg/dL and TG<150 mg/dL; a composite of standard secondary risk targets, LDL-C<100, non-HDL-C<130, TG<150; LDL phenotype; HDL-C ≥ 40; TG<150; and TG/HDL-C<3. METHODS: We measured ApoB, ApoAI, ultracentrifugation lipoprotein cholesterol and NMR lipoprotein particle concentration in 148 unselected primary and secondary prevention patients. RESULTS: TC/HDL-C<3 effectively discriminated subjects by LDL-P goal (F = 84.1, p<10(-6. The ATP-III very high risk composite target (LDL-C<70, nonHDL-C<100, TG<150 was also effective (F = 42.8, p<10(-5. However, the standard secondary prevention composite (LDL-C<100, non-HDL-C<130, TG<150 was also effective but yielded higher LDL-P than the very high risk composite (F = 42.0, p<10(-5 with upper 95% confidence interval of LDL-P less than 1000 nmol/L. TG<150 and TG/HDL-C<3 cutpoints both significantly discriminated subjects but the LDL-P upper 95% confidence intervals fell above goal of 1000 nmol/L (F = 15.8, p = 0.0001 and F = 9.7, p = 0.002 respectively. LDL density phenotype neared significance (F = 2.85, p = 0.094 and the HDL-C cutpoint of 40 mg/dL did not discriminate (F = 0.53, p = 0.47 alone or add discriminatory power to ATP-III targets. CONCLUSIONS: A simple composite of ATP-III very high risk lipoprotein cholesterol based treatment targets or TC/HDL-C ratio <3 most effectively identified subjects meeting the secondary prevention target level of LDL-P<1000 nmol/L, providing a potential alternative to advanced lipid testing in many clinical

  10. Can Infrared Spectroscopy Be Used to Measure Change in Potassium Nitrate Concentration as a Proxy for Soil Particle Movement?

    OpenAIRE

    Mila Ivanova Luleva; Harald van der Werff; Freek van der Meer; Victor Jetten

    2011-01-01

    Displacement of soil particles caused by erosion influences soil condition and fertility. To date, the cesium 137 isotope (137Cs) technique is most commonly used for soil particle tracing. However when large areas are considered, the expensive soil sampling and analysis present an obstacle. Infrared spectral measurements would provide a solution, however the small concentrations of the isotope do not influence the spectral signal sufficiently. Potassium (K) has similar electrical, chemical an...

  11. Particle concentration and flux dynamics in the atmospheric boundary layer as the indicator of formation mechanism

    DEFF Research Database (Denmark)

    Lauros, J.; Sogachev, Andrey; Smolander, S.

    2011-01-01

    We carried out column model simulations to study particle fluxes and deposition and to evaluate different particle formation mechanisms at a boreal forest site in Finland. We show that kinetic nucleation of sulphuric acid cannot be responsible for new particle formation alone as the simulated...

  12. Particle concentration and flux dynamics in the atmospheric boundary layer as the indicator of formation mechanism

    DEFF Research Database (Denmark)

    Lauros, J.; Sogachev, Andrey; Smolander, S.

    2010-01-01

    We carried out column model simulations to study particle fluxes and deposition and to evaluate different particle formation mechanisms at a boreal forest site in Finland. We show that kinetic nucleation of sulphuric acid cannot be responsible for new particle formation alone as the vertical...

  13. Quantification of solid pressure in the concentration polarization (CP) layer of colloidal particles and its impact on ultrafiltration.

    Science.gov (United States)

    Wang, Xiao-Mao; Li, Xiao-Yan; David Waite, T

    2011-06-01

    Here we describe the nature and implications of the "concentration polarization" (CP) layer that is formed during ultrafiltration of colloidal particles using a new approach in which the solid pressure, which arises from inter-particle interactions, and the inherent osmotic pressure are separately considered. The approach makes use of the particle transport mass balance between the convective and diffusive fluxes. The particle convection rate is hindered when inter-particle interactions take effect by reducing the particle velocities while the particle diffusion is solely controlled by the Brownian motion. An increase in solid pressure accounts for the reduction of the water potential caused by the relative motions of the particles and the surrounding water. A cell model is adopted to relate the local solid pressure with the local solid fraction and inter-particle interactions. The inter-particle interactions critically determine the form of particle accumulation (i.e. CP or gel/cake) on the membrane. The Shirato-Darcy equation is employed to relate the rate of increase in solid pressure, the relative liquid velocity and the solid fraction. Numerical integration approaches are employed to quantify the properties of the CP layer during both the development as well as the steady state phases (with steady state normally being achieved in a few minutes). The solid fractions are always no higher than those obtained when the inter-particle interactions are not considered. The decrease of the water potential caused by CP formation leads to the increase of both the solid pressure and the osmotic pressure. The dependence of the solid pressure on the solid fraction is usually stronger than that of the osmotic pressure. It is thus apparent that the solid pressure would be expected to dominate water potential reduction for solid fractions above a certain value though the solid pressure will be negligible when the solid fraction is relatively low.

  14. Novel concentration method for the detection of norovirus and sapovirus from water using minute particles of amorphous calcium phosphate.

    Science.gov (United States)

    Shinohara, Michiyo; Uchida, Kazue; Shimada, Shin-Ichi; Tomioka, Kyoko; Suzuki, Noriko; Minegishi, Toshitaka; Kawahashi, Sachie; Yoshikawa, Yuko; Ohashi, Norio

    2011-06-01

    A novel concentration method using minute particles of amorphous calcium phosphate (ACP) was developed for the detection of caliciviruses including norovirus and sapovirus, agents of human gastroenteritis, from water. In seeding experiments with feline calicivirus (FCV), ACP particles were able to adsorb efficiently the viruses in water, and the FCV-concentrated solution was obtained by dissolution of the virus-adsorbing ACP particles with citric acid after centrifugation. By quantitative real-time RT-PCR, the recovery efficiencies from 300 ml ultrapure water seeded with 10³, 10⁴ and >10⁵ copies of FCV were 48, 68 and >100 %, respectively. A comparative study showed that in the addition of viruses at sapovirus (genogroups I, II, IV and V) from river water. The data suggest that our new viral concentration is a rapid, simple, cost efficient and high virus recovery method, and it can be used for routine monitoring of norovirus and sapovirus in water, especially environmental water.

  15. Diffusiophoresis of concentrated suspensions of spherical particles with charge-regulated surface: polarization effect with nonlinear poisson-Boltzmann equation.

    Science.gov (United States)

    Lou, James; Shih, Chun-Yu; Lee, Eric

    2010-01-05

    Diffusiophoresis in concentrated suspensions of spherical colloids with charge-regulated surface is investigated theoretically. The charge-regulated surface considered here is the generalization of conventional constant surface potential and constant surface charge density situations. Kuwabara's unit cell model is adopted to describe the system and a pseudospectral method based on Chebyshev polynomial is employed to solve the governing general electrokinetic equations. Excellent agreements with experimental data available in literature were obtained for the limiting case of constant surface potential and very dilute suspension. It is found, among other things, that in general the larger the number of dissociated functional groups on particle surface is, the higher the particle surface potential, hence the larger the magnitude of the particle mobility. The electric potential on particle surface depends on both the concentration of dissociated hydrogen ions and the concentration of electrolyte in the solution. The electric potential on particle surface turns out to be the dominant factor in the determination of the eventual particle diffusiophoretic mobility. Local maximum of diffusiophoretic mobility as a function of double layer thickness is observed. Its reason and influence is discussed. Corresponding behavior for the constant potential situation, however, may yield a monotonously increasing profile.

  16. Correlation between polycyclic aromatic hydrocarbons concentration and airborne particle mutagenicity in the rubber factory.

    Science.gov (United States)

    Barański, B; Palus, J; Rogaczewska, T; Szymczak, W; Spiechowicz, E

    1992-01-01

    The study was undertaken to evaluate the correlation between benzo[a]pyrene and coal tar pitch volatiles concentrations and mutagenic activity of airborne particles sampled at different workplaces of the factory producing various types of tires. The solid phase of aerosols was collected on Whatman glass-fibers filters using Staplex pumps. Coal tar pitch volatiles (CTPVs) were extracted from sample filters using ultrasonic-benzene extraction and determined by the gravimetric method. Benzo[a]pyrene (BaP) analysis was performed using high performance liquid chromatography with a spectrofluorimetric detector. The mutagenic substances were extracted from collected material with acetone. The mutagenic properties were estimated with the Ames' test using S. typhimurium strain TA98 without and with S9 fraction. At nearly all workplaces the concentrations of BaP and CTPVs were within the range of 4-61 ng/m3 and 0.11-1.26 mg/m3, respectively. Only at weighing were they much higher and amounted to 172-2261 ng/m3 for BaP and 3.05-4.07 mg/m3 for CTPVs. The highest exposure to mutagenic airborne particulate matter was found at weighing (1500 rev/m3), the mixers loading level (> 500 rev/m3) and the carbon black station (> 150 rev/m3). The air mutagenic activity at other workplaces, especially at the extruder mill of the mixer (> 90 rev/m3), the two-roll mill of mixers (> 70 rev/m3), mixer I loading (> 70 rev/m3), calendering (> 70 rev/m3) and fender vulcanizing (> 80 rev/m3) was even much more higher than that found in the urban indoor and outdoor air (2-9 rev/m3).(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Particle Exposure Assessment for Community Elderly (PEACE) in Tianjin, China: Mass concentration relationships

    Science.gov (United States)

    Zhou, Jian; Han, Bin; Bai, Zhipeng; You, Yan; Zhang, Jiefeng; Niu, Can; Liu, Yating; Zhang, Nan; He, Fei; Ding, Xiao; Lu, Bing; Hu, Yandi

    2012-03-01

    Particle Exposure Assessment for Community Elderly (PEACE) in Tianjin, China was to characterize personal PM10 exposure, and provide data support for an epidemiological study investigating potential health effects of PM pollution on Chinese elderly population. In this study, a total of 80 elderly participants were recruited for a two-consecutive-day personal exposure measurement, and simultaneously residential indoor, residential outdoor and community PM10 were monitored in the summer and winter of 2009. Personal PM10 concentrations were 192.8 ± 100.6 μg m-3 in summer and 154.6 ± 105.4 μg m-3 in winter. Modeled personal exposures were less than measured personal exposures while a high coefficient of determination (R2) of 0.71 was obtained. Based on measured and modeled exposures, a mean personal cloud of 30.2 μg m-3 was estimated in summer and 16.5 μg m-3 in winter. Moderate correlation emerged between personal and community PM10 concentrations in summer (r = 0.39), and stronger correlation was found in winter (r = 0.82). Analysis of variance (ANOVA) shown that smoking, cooking and cleaning activities did not produce significant effect on personal exposures. Further more, multivariate regression analysis performed in this study revealed that community PM10 level contributed most of personal PM10 exposure, 32% in summer and 64% in winter, respectively. The findings of this study indicated that PM10 personal exposures were considerably influenced by outdoor particulate matter rather than typical indoor sources, and ambient PM10 level measured at community monitoring sites may be used as a surrogate of personal exposure to PM10.

  18. Particle size distribution, concentration, and magnetic attraction affect transport of polymer-modified Fe(0) nanoparticles in sand columns.

    Science.gov (United States)

    Phenrat, Tanapon; Kim, Hye-Jin; Fagerlund, Fritjof; Illangasekare, Tissa; Tilton, Robert D; Lowry, Gregory V

    2009-07-01

    The effect of particle concentration, size distribution (polydispersity) and magnetic attractive forces (Fe(0) content) on agglomeration and transport of poly(styrene sulfonate) (PSS) modified NZVI was studied in water-saturated sand (d(p) = 300 microm) columns. Particle concentrations ranged from 0.03 to 6 g/L in 5 mM NaCl/5 mM NaHCO3 at a pore water velocity of 3.2 x 10(-4) m/s. Three NZVI dispersions with different intrinsic particle size distributions obtained from sequential sedimentation are compared. The influence of magnetic attraction (Fe(0) content) on NZVI agglomeration and deposition in porous media is assessed by comparing the deposition behavior of PSS-modified NZVI (magnetic) having different Fe(0) contents with PSS-modified hematite (nonmagnetic) with the same surface modifier. At low particle concentration (30 mg/L) all particles were mobile in sand columns regardless of size or magnetic attractive forces. At high concentration (1 to 6 g/L), deposition of the relatively monodisperse dispersion containing PSS-modified NZVI (hydrodynamic radius (R(H)) = 24 nm) with the lowest Fe(0) content (4 wt%) is low (attachment efficiency (alpha) = 2.5 x 10(-3)), insensitive to particle concentration, and similar to PSS-modified hematite. At 1 to 6 g/L, the attachment efficiency of polydisperse dispersions containing both primary particles and sintered aggregates (R(H) from 15 to 260 nm) of PSS-modified NZVI with a range of Fe(0) content (10-60%) is greater (alpha = 1.2 x 10(-2) to 7.2 x 10(-2) and is sensitive to particle size distribution. The greater attachment for larger, more polydisperse Fe(0) nanoparticles with higher Fe(0) content is a result of their agglomeration during transport in porous media because the magnetic attractive force between particles increases with the sixth power of particle/agglomerate radius. A filtration model that considers agglomeration in porous media and subsequent deposition explains the observed transport of polydisperse PSS

  19. Can infrared spectroscopy be used to measure change in potassium nitrate concentration as a proxy for soil particle movement?

    Science.gov (United States)

    Luleva, Mila Ivanova; van der Werff, Harald; Jetten, Victor; van der Meer, Freek

    2011-01-01

    Displacement of soil particles caused by erosion influences soil condition and fertility. To date, the cesium 137 isotope ((137)Cs) technique is most commonly used for soil particle tracing. However when large areas are considered, the expensive soil sampling and analysis present an obstacle. Infrared spectral measurements would provide a solution, however the small concentrations of the isotope do not influence the spectral signal sufficiently. Potassium (K) has similar electrical, chemical and physical properties as Cs. Our hypothesis is that it can be used as possible replacement in soil particle tracing. Soils differing in texture were sampled for the study. Laboratory soil chemical analyses and spectral sensitivity analyses were carried out to identify the wavelength range related to K concentration. Different concentrations of K fertilizer were added to soils with varying texture properties in order to establish spectral characteristics of the absorption feature associated with the element. Changes in position of absorption feature center were observed at wavelengths between 2,450 and 2,470 nm, depending on the amount of fertilizer applied. Other absorption feature parameters (absorption band depth, width and area) were also found to change with K concentration with coefficient of determination between 0.85 and 0.99. Tracing soil particles using K fertilizer and infrared spectral response is considered suitable for soils with sandy and sandy silt texture. It is a new approach that can potentially grow to a technique for rapid monitoring of soil particle movement over large areas.

  20. Can Infrared Spectroscopy Be Used to Measure Change in Potassium Nitrate Concentration as a Proxy for Soil Particle Movement?

    Directory of Open Access Journals (Sweden)

    Mila Ivanova Luleva

    2011-04-01

    Full Text Available Displacement of soil particles caused by erosion influences soil condition and fertility. To date, the cesium 137 isotope (137Cs technique is most commonly used for soil particle tracing. However when large areas are considered, the expensive soil sampling and analysis present an obstacle. Infrared spectral measurements would provide a solution, however the small concentrations of the isotope do not influence the spectral signal sufficiently. Potassium (K has similar electrical, chemical and physical properties as Cs. Our hypothesis is that it can be used as possible replacement in soil particle tracing. Soils differing in texture were sampled for the study. Laboratory soil chemical analyses and spectral sensitivity analyses were carried out to identify the wavelength range related to K concentration. Different concentrations of K fertilizer were added to soils with varying texture properties in order to establish spectral characteristics of the absorption feature associated with the element. Changes in position of absorption feature center were observed at wavelengths between 2,450 and 2,470 nm, depending on the amount of fertilizer applied. Other absorption feature parameters (absorption band depth, width and area were also found to change with K concentration with coefficient of determination between 0.85 and 0.99. Tracing soil particles using K fertilizer and infrared spectral response is considered suitable for soils with sandy and sandy silt texture. It is a new approach that can potentially grow to a technique for rapid monitoring of soil particle movement over large areas.

  1. Comparison of sp-ICP-MS and MDG-ICP-MS for the determination of particle number concentration.

    Science.gov (United States)

    Gschwind, Sabrina; Aja Montes, Maria de Lourdes; Günther, Detlef

    2015-05-01

    In 2011, the European Commission introduced new regulations on how nanomaterials are defined. Since then, researchers have emphasized that more complete characterization of nanoparticles (NPs) includes not just mass and size determinations, but also the determination of the particle number concentrations. In this study, two different sample introduction approaches for the analysis of NP suspensions with inductively coupled plasma mass spectrometry (ICP-MS) were investigated: pneumatic nebulization (sp-ICP-MS) and microdroplet generation (MDG-ICP-MS). These approaches were compared for the determination of particle number concentrations (PNCs) of gold and silver NP suspensions diluted in either ultra-pure water or citrate solution. For accurate sp-ICP-MS analysis, it is crucial to know the transport efficiency of nebulized sample into the plasma. Here, transport efficiencies, measured by the waste collection method, were 11-14 % for Ag suspensions and 9-11 % for Au. In contrast, the droplet transport efficiency of MDG-ICP-MS was 100 %. Analysis by sp-ICP-MS yielded a lower particle number concentration than expected (only 20-40 % of the expected value), whereas MDG-ICP-MS had NP recoveries up to 80 %. This study indicates that NP reference materials are of major importance for particle number determination and detailed results on particle number concentrations for different suspensions with respect to storage time are discussed.

  2. Coupling Discrete and Continuum Mechanics in Low Concentration, Particle-Laden Flows

    Science.gov (United States)

    Boyle, Paul; Houchens, Brent; Kim, Albert

    2008-11-01

    The study of particle-laden flow plays a critical role in pressure-driven membrane filtration such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). Hydrodynamic and inter-particle interactions, coupled to the ambient crossflow field, are well documented in literature. Transport of particles is originated due to Brownian and shear-induced diffusion, and convection due to the axial crossflow and transverse permeate flow. These effects are modeled using Hydrodynamic Force Bias Monte Carlo (HFBMC) simulations to predict the deposition of the particles on the membrane surface. In addition, the particles in the simulation are also subject to electrostatic double layer repulsion and van der Waals attraction both between particles and between the particles and membrane surfaces. In conjunction with the hydrodynamics, the change in particle potential determines the transition probability that a proposed, random move of a particle will be accepted. In the current study, these discrete particle effects at the microscopic level are coupled to the continuum flow via an apparent local viscosity, yielding a quasi-steady-state velocity profile. This velocity profile is dynamically updated in order to refine the hydrodynamic interactions. The resulting simulation predicts the formation of a cake layer of deposited interacting particles on the membrane surface.

  3. A method based on light scattering to estimate the concentration of virus particles without the need for virus particle standards

    Directory of Open Access Journals (Sweden)

    István Makra

    2015-01-01

    • The concentration of virus nanoparticles can be calculated based on the two measured scattered light intensities by knowing the refractive index of the dispersing solution, of the polymer and virus nanoparticles as well as their relative sphere equivalent diameters.

  4. Prediction of indoor concentration of 0.5-4 µm particles of outdoor origin in an uninhabited apartment

    DEFF Research Database (Denmark)

    Schneider, T.; Jensen, K.A.; Clausen, P.A.

    2004-01-01

    was estimated from concentration rebound measurements following HEPA filtering of the indoor air by fitting a simple deterministic model. The model included measured air exchange rates and published surface deposition loss rates. This model was then used to predict indoor particle concentration. The model...... apartments. The results suggest that factors such as particle chemical composition, within building transport patterns, and occupant behaviour in other apartments should be identified and quantified in future studies, and that these factors need to be included in predictive models. (C) 2004 Elsevier Ltd. All...

  5. Impacts of biochar concentration and particle size on hydraulic conductivity and DOC leaching of biochar-sand mixtures

    Science.gov (United States)

    Liu, Zuolin; Dugan, Brandon; Masiello, Caroline A.; Barnes, Rebecca T.; Gallagher, Morgan E.; Gonnermann, Helge

    2016-02-01

    The amendment of soil with biochar can sequester carbon and alter hydrologic properties by changing physical and chemical characteristics of soil. To understand the effect of biochar amendment on soil hydrology, we measured the hydraulic conductivity (K) of biochar-sand mixtures as well as dissolved organic carbon (DOC) in leachate. Specifically, we assessed the effects of biochar concentration and particle size on K and amount of DOC in the soil leachate. To better understand how physical properties influenced K, we also measured the skeletal density of biochars and sand, and the bulk density, the water saturation, and the porosity of biochar-sand mixtures. Our model soil was sand (0.251-0.853 mm) with biochar rates from 2 to 10 wt% (g biochar/g total soil × 100%). As biochar (concentration increased from 0 to 10 wt%, K decreased by 72 ± 3%. When biochar particle size was equal to, greater than, and less than particle size of sand, we found that biochar in different particle sizes have different effects on K. For a 2 wt% biochar rate, K decreased by 72 ± 2% when biochar particles were finer than sand particles, and decreased by 15 ± 2% when biochar particles were coarser than sand particles. When biochar and sand particle size were comparable, we observed no significant effect on K. We propose that the decrease of K through the addition of fine biochar was because finer biochar particles filled spaces between sand particles, which increased tortuosity and reduced pore throat size of the mixture. The decrease of K associated with coarser biochar was caused by the bimodal particle size distribution, resulting in more compact packing and increased tortuosity. The loss of biochar C as DOC was related to both biochar rate and particle size. The cumulative DOC loss was 1350% higher from 10 wt% biochar compared to pure sand. This large increase reflected the very small DOC yield from pure sand. In addition, DOC in the leachate decreased as biochar particle size

  6. Simulation of particle size distribution with a global aerosol model: contribution of nucleation to aerosol and CCN number concentrations

    Directory of Open Access Journals (Sweden)

    F. Yu

    2009-04-01

    Full Text Available An advanced particle microphysics model with a number of computationally efficient schemes has been incorporated into a global chemistry transport model (GEOS-Chem to simulate particle number size distributions and cloud condensation nuclei (CCN concentrations in the atmosphere. Size-resolved microphysics for secondary particles (i.e., those formed from gaseous species and sea salt has been treated in the present study. The growth of nucleated particles through the condensation of sulfuric acid vapor and equilibrium uptake of nitrate, ammonium, and secondary organic aerosol is explicitly simulated, along with the scavenging of secondary particles by primary particles (dust, black carbon, organic carbon, and sea salt. We calculate secondary particle formation rate based on ion-mediated nucleation (IMN mechanism and constrain the parameterizations of primary particle emissions with various observations. Our simulations indicate that secondary particles formed via IMN appear to be able to account for the particle number concentrations observed in many parts of troposphere. A comparison of the simulated annual mean concentrations of condensation nuclei larger than 10 nm (CN10 with those measured values show very good agreement (within a factor of two in near all 22 sites around the globe that have at least one full year of CN10 measurements. Secondary particles appear to dominate the number abundance in most parts of the troposphere. Calculated CCN concentration at supersaturation of 0.4% (CCN0.4 and the fraction of CCN0.4 that is secondary (fCCNsec have large spatial variations. Over the middle latitude in the Northern Hemisphere, zonally averaged CCN0.4 decreases from ~400–700 cm−3 in the boundary layer (BL to below 100 cm−3 above altitude of ~4 km, the corresponding fCCNsec values change from 50–60% to above ~70%. In the Southern Hemisphere, the zonally

  7. Simulation of particle size distribution with a global aerosol model: contribution of nucleation to aerosol and CCN number concentrations

    Directory of Open Access Journals (Sweden)

    F. Yu

    2009-10-01

    Full Text Available An advanced particle microphysics model with a number of computationally efficient schemes has been incorporated into a global chemistry transport model (GEOS-Chem to simulate particle number size distributions and cloud condensation nuclei (CCN concentrations in the atmosphere. Size-resolved microphysics for secondary particles (i.e., those formed from gaseous species and sea salt has been treated in the present study. The growth of nucleated particles through the condensation of sulfuric acid vapor and equilibrium uptake of nitrate, ammonium, and secondary organic aerosol is explicitly simulated, along with the scavenging of secondary particles by primary particles (dust, black carbon, organic carbon, and sea salt. We calculate secondary particle formation rate based on ion-mediated nucleation (IMN mechanism and constrain the parameterizations of primary particle emissions with various observations. Our simulations indicate that secondary particles formed via IMN appear to be able to account for the particle number concentrations observed in many parts of the troposphere. A comparison of the simulated annual mean concentrations of condensation nuclei larger than 10 nm (CN10 with those measured values show very good agreement (within a factor of two in near all 22 sites around the globe that have at least one full year of CN10 measurements. Secondary particles appear to dominate the number abundance in most parts of the troposphere. Calculated CCN concentration at supersaturation of 0.4% (CCN0.4 and the fraction of CCN0.4 that is secondary (fsecCCN have large spatial variations. Over the middle latitude in the Northern Hemisphere, zonally averaged CCN0.4 decreases from ~400–700 cm−3 in the boundary layer (BL to below 100 cm−3 above altitude of ~4 km, the corresponding fsecCCN values change from 50–60% to above ~70%. In the Southern Hemisphere, the zonally

  8. Source apportionment of PM2.5 chemically speciated mass and particle number concentrations in New York City

    Science.gov (United States)

    Masiol, M.; Hopke, P. K.; Felton, H. D.; Frank, B. P.; Rattigan, O. V.; Wurth, M. J.; LaDuke, G. H.

    2017-01-01

    The major sources of fine particulate matter (PM2.5) in New York City (NYC) were apportioned by applying positive matrix factorization (PMF) to two different sets of particle characteristics: mass concentrations using chemical speciation data and particle number concentrations (PNC) using number size distribution, continuously monitored gases, and PM2.5 data. Post-processing was applied to the PMF results to: (i) match with meteorological data, (ii) use wind data to detect the likely locations of the local sources, and (iii) use concentration weighted trajectory models to assess the strength of potential regional/transboundary sources. Nine sources of PM2.5 mass were apportioned and identified as: secondary ammonium sulfate, secondary ammonium nitrate, road traffic exhaust, crustal dust, fresh sea-salt, aged sea-salt, biomass burning, residual oil/domestic heating and zinc. The sources of PNC were investigated using hourly average number concentrations in six size bins, gaseous air pollutants, mass concentrations of PM2.5, particulate sulfate, OC, and EC. These data were divided into 3 periods indicative of different seasonal conditions. Five sources were resolved for each period: secondary particles, road traffic, NYC background pollution (traffic and oil heating largely in Manhattan), nucleation and O3-rich aerosol. Although traffic does not account for large amounts of PM2.5 mass, it was the main source of particles advected from heavily trafficked zones. The use of residual oil had limited impacts on PM2.5 mass but dominates PNC in cold periods.

  9. Characterisation of particle mass and number concentration on the east coast of the Malaysian Peninsula during the northeast monsoon

    Science.gov (United States)

    Dominick, Doreena; Latif, Mohd Talib; Juneng, Liew; Khan, Md Firoz; Amil, Norhaniza; Mead, Mohammed Iqbal; Nadzir, Mohd Shahrul Mohd; Moi, Phang Siew; Samah, Azizan Abu; Ashfold, Matthew J.; Sturges, William T.; Harris, Neil R. P.; Robinson, Andrew D.; Pyle, John A.

    2015-09-01

    Particle mass concentrations (PM10, PM2.5 and PM1) and particle number concentration ((PNC); 0.27 μm ≤ Dp ≤ 34.00 μm) were measured in the tropical coastal environment of Bachok, Kelantan on the Malaysian Peninsula bordering the southern edge of the South China Sea. Statistical methods were applied on a three-month hourly data set (9th January to 24th March 2014) to study the influence of north-easterly winds on the patterns of particle mass and PNC size distributions. The 24-h concentrations of particle mass obtained in this study were below the standard values detailed by the Recommended Malaysian Air Quality Guideline (RMAQG), United States Environmental Protection Agency (US EPA) and European Union (EU) except for PM2.5, which recorded a 24-h average of 30 ± 18 μg m-3 and exceeded the World Health Organisation (WHO) threshold value (25 μg m-3). Principal component analysis (PCA) revealed that PNC with smaller diameter sizes (0.27-4.50 μm) showed a stronger influence, accounting for 57.6% of the variability in PNC data set. Concentrations of both particle mass and PNC increased steadily in the morning with a distinct peak observed at around 8.00 h, related to a combination of dispersion of accumulated particles overnight and local traffic. In addition to local anthropogenic, agricultural burning and forest fire activities, long-range transport also affects the study area. Hotspot and backward wind trajectory observations illustrated that the biomass burning episode (around February-March) significantly influenced PNC. Meteorological parameters influenced smaller size particles (i.e. PM1 and Dp (0.27-0.43 μm)) the most.

  10. Occupational exposures and determinants of ultrafine particle concentrations during laser hair removal procedures

    National Research Council Canada - National Science Library

    Emily J Eshleman; Mallory LeBlanc; Lisa B Rokoff; Yinyin Xu; Rui Hu; Kachiu Lee; Gary S Chuang; Gary Adamkiewicz; Jaime E Hart

    2017-01-01

    Background Occupational exposures to ultrafine particles in the plume generated during laser hair removal procedures, the most commonly performed light based cosmetic procedure, have not been thoroughly characterized...

  11. Influence of Electrolyte Concentration on the Aggregation Of Colloidal Particles Near Electrodes in Oscillatory Fields

    Science.gov (United States)

    Bukosky, Scott; Saini, Sukhleen; Ristenpart, William

    2016-11-01

    Micron-scale particles suspended in various aqueous electrolytes have been widely observed to aggregate near electrodes in response to oscillatory electric fields, a phenomenon believed to result from electrically induced flows around the particles. Most work has focused on a narrow range of ionic strengths. Here we demonstrate that an applied field causes micron-scale particles in aqueous NaCl to rapidly aggregate over a wide range of ionic strengths, but with significant differences in aggregation morphology. Optical microscopy observations reveal that at higher ionic strengths ( 1 mM) particles arrange as hexagonally closed-packed (HCP) crystals, but at lower ionic strengths ( 0.05 mM) the particles arrange in randomly closed-packed (RCP) structures. We interpret this behavior in terms of two complementary effects: an increased particle diffusivity at lower ionic strengths due to increased particle height over the electrode and the existence of a deep secondary minimum in the particle pair interaction potential at higher ionic strength that traps particles in close proximity to one another. The results suggest that electrically induced crystallization will readily occur only over a narrow range of ionic strengths.

  12. Particle concentrating and sorting under a rotating electric field by direct optical-liquid heating in a microfluidics chip.

    Science.gov (United States)

    Chen, Yu-Liang; Jiang, Hong-Ren

    2017-05-01

    We demonstrate a functional rotating electrothermal technique for rapidly concentrating and sorting a large number of particles on a microchip by the combination of particle dielectrophoresis (DEP) and inward rotating electrothermal (RET) flows. Different kinds of particles can be attracted (positive DEP) to or repelled (negative DEP) from electrode edges, and then the n-DEP responsive particles are further concentrated in the heated region by RET flows. The RET flows arise from the spatial inhomogeneous electric properties of fluid caused by direct infrared laser (1470 nm) heating of solution in a rotating electric field. The direction of the RET flows is radially inward to the heated region with a co-field (the same as the rotating electric field) rotation. Moreover, the velocity of the RET flows is proportional to the laser power and the square of the electric field strength. The RET flows are significant over a frequency range from 200 kHz to 5 MHz. The RET flows are generated by the simultaneous application of the infrared laser and the rotating electric field. Therefore, the location of particle concentrating can be controlled within the rotating electric field depending on the position of the laser spot. This multi-field technique can be operated in salt solutions and at higher frequency without external flow pressure, and thus it can avoid electrokinetic phenomena at low frequency to improve the manipulation accuracy for lab-on-chip applications.

  13. Determination of size and concentration of particles in air by using long-path optical extinction measurements

    Science.gov (United States)

    Paganini, Enrico; Perini, Umberto U.; Trespidi, Franco; Ferri, Fabio

    1999-09-01

    Atmospheric particle pollution and particles emitted by industrial plants are extremely dangerous for human health. Indeed, they have diameters in such a range (approximately 0.1 - 5 micrometer) that they can penetrate our respiratory system, but cannot be expelled during exhalation. Therefore, it is extremely important to detect them and characterize their size distribution. In this paper we propose the use of a novel instrument recently developed by the authors for the monitoring of airborne particulate at concentration levels so to comply with the current European Economic Community (EEC) regulations. The instrument is based on spectral extinction measurements over long optical paths and is able to recover, almost in real time, both concentration and size distribution of particles with diameters in the range of interest. The sensitivity and accuracy of the instrument were estimated by means of measurements in a clean room and by using calibrated particles dispersed in water. Our results show that, by carrying out measurements over optical paths of approximately$DAL100m, the instrument is able to detect concentration levels well below the ECC limit imposed for the atmospheric pollution. Scaled over shorter optical paths (approximately 10 m), the limit imposed for particle emissions by industrial plants can also be detected very accurately.

  14. Trends in black carbon and size-resolved particle number concentrations and vehicle emission factors under real-world conditions

    Science.gov (United States)

    Krecl, Patricia; Johansson, Christer; Targino, Admir Créso; Ström, Johan; Burman, Lars

    2017-09-01

    Kerbside concentrations of NOx, black carbon (BC), total number of particles (diameter > 4 nm) and number size distribution (28-410 nm) were measured at a busy street canyon in Stockholm in 2006 and 2013. Over this period, there was an important change in the vehicle fleet due to a strong dieselisation process of light-duty vehicles and technological improvement of vehicle engines. This study assesses the impact of these changes on ambient concentrations and particle emission factors (EF). EF were calculated by using a novel approach which combines the NOx tracer method with positive matrix factorisation (PMF) applied to particle number size distributions. NOx concentrations remained rather constant between these two years, whereas a large decrease in particle concentrations was observed, being on average 60% for BC, 50% for total particle number, and 53% for particles in the range 28-100 nm. The PMF analysis yielded three factors that were identified as contributions from gasoline vehicles, diesel fleet, and urban background. This separation allowed the calculation of the average vehicle EF for each particle metric per fuel type. In general, gasoline EF were lower than diesel EF, and EF for 2013 were lower than the ones derived for 2006. The EFBC decreased 77% for both gasoline and diesel fleets, whereas the particle number EF reduction was higher for the gasoline (79%) than for the diesel (37%) fleet. Our EF are consistent with results from other on-road studies, which reinforces that the proposed methodology is suitable for EF determination and to assess the effectiveness of policies implemented to reduce vehicle exhaust emissions. However, our EF are much higher than EF simulated with traffic emission models (HBEFA and COPERT) that are based on dynamometer measurements, except for EFBC for diesel vehicles. This finding suggests that the EF from the two leading models in Europe should be revised for BC (gasoline vehicles) and particle number (all vehicles

  15. Tangential Flow Ultrafiltration Allows Purification and Concentration of Lauric Acid-/Albumin-Coated Particles for Improved Magnetic Treatment

    Directory of Open Access Journals (Sweden)

    Jan Zaloga

    2015-08-01

    Full Text Available Superparamagnetic iron oxide nanoparticles (SPIONs are frequently used for drug targeting, hyperthermia and other biomedical purposes. Recently, we have reported the synthesis of lauric acid-/albumin-coated iron oxide nanoparticles SEONLA-BSA, which were synthesized using excess albumin. For optimization of magnetic treatment applications, SPION suspensions need to be purified of excess surfactant and concentrated. Conventional methods for the purification and concentration of such ferrofluids often involve high shear stress and low purification rates for macromolecules, like albumin. In this work, removal of albumin by low shear stress tangential ultrafiltration and its influence on SEONLA-BSA particles was studied. Hydrodynamic size, surface properties and, consequently, colloidal stability of the nanoparticles remained unchanged by filtration or concentration up to four-fold (v/v. Thereby, the saturation magnetization of the suspension can be increased from 446.5 A/m up to 1667.9 A/m. In vitro analysis revealed that cellular uptake of SEONLA-BSA changed only marginally. The specific absorption rate (SAR was not greatly affected by concentration. In contrast, the maximum temperature Tmax in magnetic hyperthermia is greatly enhanced from 44.4 °C up to 64.9 °C by the concentration of the particles up to 16.9 mg/mL total iron. Taken together, tangential ultrafiltration is feasible for purifying and concentrating complex hybrid coated SPION suspensions without negatively influencing specific particle characteristics. This enhances their potential for magnetic treatment.

  16. Tangential Flow Ultrafiltration Allows Purification and Concentration of Lauric Acid-/Albumin-Coated Particles for Improved Magnetic Treatment.

    Science.gov (United States)

    Zaloga, Jan; Stapf, Marcus; Nowak, Johannes; Pöttler, Marina; Friedrich, Ralf P; Tietze, Rainer; Lyer, Stefan; Lee, Geoffrey; Odenbach, Stefan; Hilger, Ingrid; Alexiou, Christoph

    2015-08-14

    Superparamagnetic iron oxide nanoparticles (SPIONs) are frequently used for drug targeting, hyperthermia and other biomedical purposes. Recently, we have reported the synthesis of lauric acid-/albumin-coated iron oxide nanoparticles SEON(LA-BSA), which were synthesized using excess albumin. For optimization of magnetic treatment applications, SPION suspensions need to be purified of excess surfactant and concentrated. Conventional methods for the purification and concentration of such ferrofluids often involve high shear stress and low purification rates for macromolecules, like albumin. In this work, removal of albumin by low shear stress tangential ultrafiltration and its influence on SEON(LA-BSA) particles was studied. Hydrodynamic size, surface properties and, consequently, colloidal stability of the nanoparticles remained unchanged by filtration or concentration up to four-fold (v/v). Thereby, the saturation magnetization of the suspension can be increased from 446.5 A/m up to 1667.9 A/m. In vitro analysis revealed that cellular uptake of SEON(LA-BSA) changed only marginally. The specific absorption rate (SAR) was not greatly affected by concentration. In contrast, the maximum temperature Tmax in magnetic hyperthermia is greatly enhanced from 44.4 °C up to 64.9 °C by the concentration of the particles up to 16.9 mg/mL total iron. Taken together, tangential ultrafiltration is feasible for purifying and concentrating complex hybrid coated SPION suspensions without negatively influencing specific particle characteristics. This enhances their potential for magnetic treatment.

  17. Programming of mouse obesity by maternal exposure to concentrated ambient fine particles.

    Science.gov (United States)

    Chen, Minjie; Wang, Xiaoke; Hu, Ziying; Zhou, Huifen; Xu, Yanyi; Qiu, Lianglin; Qin, Xiaobo; Zhang, Yuhao; Ying, Zhekang

    2017-06-23

    Many diseases including obesity may originate through alterations in the early-life environment that interrupts fetal development. Increasing evidence has shown that exposure to ambient fine particles (PM2.5) is associated with abnormal fetal development. However, its long-term metabolic effects on offspring have not been systematically investigated. To determine if maternal exposure to PM2.5 programs offspring obesity, female C57Bl/6j mice were exposed to filtered air (FA) or concentrated ambient PM2.5 (CAP) during pre-conception, pregnancy, and lactation, and the developmental and metabolic responses of offspring were assessed. The growth trajectory of offspring revealed that maternal exposure to CAP significantly decreased offspring birth weight but increased body weight of adult male but not female offspring, and the latter was expressed as increased adiposity. These adult male offspring had increased food intake, but were sensitive to exogenous leptin. Their hypothalamic expression of Socs3 and Pomc, two target genes of leptin, was not changed, and the hypothalamic expression of NPY, an orexigenic peptide that is inhibited by leptin, was significantly increased. These decreases in central anorexigenic signaling were accompanied by reduced plasma leptin and its expression in adipose tissues, the primary source of circulating leptin. In contrast, maternal exposure did not significantly change any of these indexes in adult female offspring. Pyrosequencing demonstrated that the leptin promoter methylation of adipocytes was significantly increased in CAP-exposed male but not female offspring. Our data indicate that maternal exposure to ambient PM2.5 programs obesity in male offspring probably through alterations in the methylation of the promoter region of the leptin gene.

  18. Fluorescent biological aerosol particle concentrations and size distributions measured with an Ultraviolet Aerodynamic Particle Sizer (UV-APS in Central Europe

    Directory of Open Access Journals (Sweden)

    J. A. Huffman

    2010-04-01

    Full Text Available Primary Biological Aerosol Particles (PBAPs, including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany we used an Ultraviolet Aerodynamic Particle Sizer (UV-APS to measure Fluorescent Biological Aerosol Particles (FBAPs, which provide an estimate of viable bioaerosol particles and can be regarded as an approximate lower limit for the actual abundance of PBAPs. Fluorescence of non-biological aerosol components are likely to influence the measurement results obtained for fine particles (<1 μm, but not for coarse particles (1–20 μm.

    Averaged over the four-month measurement period (August–December 2006, the mean number concentration of coarse FBAPs was ~3×10−2 cm−3, corresponding to ~4% of total coarse particle number. The mean mass concentration of FBAPs was ~1μg m−3, corresponding to ~20% of total coarse particle mass. The FBAP number size distributions exhibited alternating patterns with peaks at various diameters. A pronounced peak at ~3 μm was essentially always observed and can be described by the following campaign-average lognormal fit parameters: geometric mean diameter 3.2 μm, geometric standard deviation 1.3, number concentration 1.6×10−2 cm−3. This peak is likely due to fungal spores or agglomerated bacteria, and it exhibited a pronounced diel cycle (24-h with maximum intensity during early/mid-morning. FBAP peaks around ~1.5 μm, ~5 μm, and ~13 μm were also observed, but less pronounced and less frequent. These may be single bacterial cells, larger fungal spores, and pollen grains, respectively.

    The observed number

  19. Fluorescent biological aerosol particle concentrations and size distributions measured with an ultraviolet aerodynamic particle sizer (UV-APS in Central Europe

    Directory of Open Access Journals (Sweden)

    J. A. Huffman

    2009-08-01

    Full Text Available Primary biological aerosol particles (PBAPs, including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany, we used an ultraviolet aerodynamic particle sizer (UV-APS to measure fluorescent biological aerosol particles (FBAPs, which can be regarded as viable bioaerosol particles representing a lower limit for the actual abundance of PBAPs. Fluorescence of non-biological aerosol components are likely to influence the measurement results obtained for fine particles (<1 μm, but not for coarse particles (1–20 μm.

    Averaged over the four-month measurement period (August–December 2006, the mean number concentration of coarse FBAPs was ~3×10−2 cm−3, corresponding to ~4% of total coarse particle number. The mean mass concentration of FBAPs was ~1 μg m−3, corresponding to ~20% of total coarse particle mass. The FBAP number size distributions exhibited alternating patterns with peaks at various diameters. A pronounced peak at ~3 μm was essentially always observed and can be described by the following campaign-average lognormal fit parameters: geometric mean diameter 3.2 μm, geometric standard deviation 1.3, number concentration 1.6×10−2 cm−3. This peak is likely due to fungal spores or agglomerated bacteria, and it exhibited a pronounced diel cycle with maximum intensity during early/mid-morning. FBAP peaks around ~1.5 μm, ~5 μm, and ~13 μm were also observed, but less pronounced and less frequent. These may be explained by single bacterial cells, larger fungal spores, and pollen grains, respectively.

    The observed number concentrations and

  20. Radial pressure in the solar nebula as affecting the motions of planetesimals. [toroidal particle concentration in planetary evolution

    Science.gov (United States)

    Whipple, F. L.

    1973-01-01

    Growing planetesimals and a range of drag laws depending on the Reynolds number and on the ratio of particle size to mean free path are considered. Particles spiral in the direction of positive gradient, thus being concentrated toward toroidal concentrations of gas. The effect increases with decreasing rates of particle growth, i.e., with increasing time scales of planet formation by accretion. In the outer regions, where evidence suggests that comets were formed and Uranus and Neptune were so accumulated, the effect of the pressure gradient is to clear the forming comets from those regions. The large mass of Neptune may have developed because of this effect, perhaps Neptune's solar distance was reduced from Bode's law, and perhaps no comet belt exists beyond Neptune. In the asteroid belt, on a slow time scale, the effect may have spiraled planetesimals toward Mars and Jupiter, thus contributing to the lack of planet formation in this region.

  1. Characterization of fluidization regime in circulating fluidized bed reactor with high solid particle concentration using computational fluid dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Chalermsinsuwan, Benjapon; Thummakul, Theeranan; Piumsomboon, Pornpote [Chulalongkorn University, Bangkok (Thailand); Gidaspow, Dimitri [Armour College of Engineering, Chicago (United States)

    2014-02-15

    The hydrodynamics inside a high solid particle concentration circulating fluidized bed reactor was investigated using computational fluid dynamics simulation. Compared to a low solid particle reactor, all the conventional fluidization regimes were observed. In addition, two unconventional fluidization regimes, circulating-turbulent and dense suspension bypassing regimes, were found with only primary gas injection. The circulating-turbulent fluidization regime showed uniformly dense solid particle distribution in all the system directions, while the dense suspension bypassing fluidization regime exhibited the flow of solid particles at only one side system wall. Then, comprehensive fluidization regime clarification and mapping were evaluated using in-depth system parameters. In the circulating-turbulent fluidization regime, the total granular temperature was low compared to the adjacent fluidization regimes. In the dense suspension bypassing fluidization regime, the highest total granular temperature was obtained. The circulating-turbulent and dense suspension bypassing fluidization regimes are suitable for sorption and transportation applications, respectively.

  2. Continuous Measurement of Number Concentrations and Elemental Composition of Aerosol Particles for a Dust Storm Event in Beijing

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A continuous measurement of number size distributions and chemical composition of aerosol particles was conducted in Beijing in a dust storm event during 21-26 March 2001. The number concentration of coarse particles (>2μm) increased more significantly than fine particles (<2μm) during the dust storm due to dust weather, while the anthropogenic aerosols collected during the non-dust-storm period tended to be associated with fine particles. Elemental compositions were analyzed by using proton-induced X-ray emission (PIXE). The results show that 20 elements in the dust storm were much higher than in the non-dust-storm period. The calculated soil dust concentration during the dust storm was, on average, 251.8μg m-3, while it was only 52.1 μg m-3 on non-dust-storm days. The enrichment factors for Mg, Al, P, K, Ca, Ti, Mn, Fe, Cl, Cu, Pb, and Zn show small variations between the dust storm and the non-dust-storm period, while those for Ca, Ni and Cr in the dust storm were much lower than those in the non-dust-storm period due to significant local emission sources. A high concentration and enrichment factor for S were observed during the dust storm, which implies that the dust particles were contaminated by aerosol particles from anthropogenic emissions during the long-range transport. A statistical analysis shows that the elemental composition of particles collected during the dust storm in Beijing were better correlated with those of desert soil colleted from desert regions in Inner Mongolia. Air mass back-trajectory analysis further confirmed that this dust storm event could be identified as streaks of dust plumes originating from Inner Mongolia.

  3. Changes in lipids and lipoprotein particle concentrations after interruption of antiretroviral therapy

    DEFF Research Database (Denmark)

    Lampe, Fiona C; Duprez, Daniel A; Kuller, Lewis H

    2010-01-01

    The effect of interruption of antiretroviral therapy (ART) on lipoprotein particle subclasses has not been studied. We examined short-term changes in lipids and lipoprotein particles among 332 HIV-infected individuals randomized to interrupt or continue ART in the "Strategies for Management...... of Antiretroviral Therapy" trial....

  4. Primary versus secondary contributions to particle number concentrations in the European boundary layer

    NARCIS (Netherlands)

    Reddington, C.L.; Carslaw, K.S.; Spracklen, D.V.; Frontoso, M.G.; Collins, L.; Merikanto, J.; Minikin, A.; Hamburger, T.; Coe, H.; Kulmala, M.; Aalto, P.; Flentje, H.; Plass-Dülmer, C.; Birmili, W.; Wiedensohler, A.; Wehner, B.; Tuch, T.; Sonntag, A.; O'Dowd, C.D.; Jennings, S.G.; Dupuy, R.; Baltensperger, U.; Weingartner, E.; Hansson, H.-C.; Tunved, P.; Laj, P.; Sellegri, K.; Boulon, J.; Putaud, J.-P.; Gruening, C.; Swietlicki, E.; Roldin, P.; Henzing, J.S.; Moerman, M.; Mihalopoulos, N.; Kouvarakis, G.; Ždímal, V.; Zíková, N.; Marinoni, A.; Bonasoni, P.; Duchi, R.

    2011-01-01

    It is important to understand the relative contribution of primary and secondary particles to regional and global aerosol so that models can attribute aerosol radiative forcing to different sources. In large-scale models, there is considerable uncertainty associated with treatments of particle forma

  5. Amino-functionalized breath-figure cavities in polystyrene-alumina hybrid films: effect of particle concentration and dispersion.

    Science.gov (United States)

    V, Lakshmi; Raju, Annu; V G, Resmi; Pancrecious, Jerin K; T P D, Rajan; C, Pavithran

    2016-03-14

    We report the formation of breath-figure (BF) patterns with amino-functionalized cavities in a BF incompatible polystyrene (PS) by incorporating functionalized alumina nanoparticles. The particles were amphiphilic-modified and the modifier ratio was regulated to achieve a specific hydrophobic/hydrophilic balance of the particles. The influence of the physical and chemical properties of the particles like particle concentration, the hydrophobic/hydrophilic balance, etc., on particle dispersion in solvents having different polarity and the corresponding changes in the BF patterns have been studied. The amphiphilic-modified alumina particles could successfully assist the BF mechanism, generating uniform patterns in polystyrene films with the cavity walls decorated with the functionalized alumina particles, even from water-miscible solvents like THF. The possibility of fabricating free-standing micropatterned films by casting and drying the suspension under ambient conditions was also demonstrated. The present method opens up a simple route for producing functionalized BF cavities, which can be post-modified by a chemical route for various biological applications.

  6. Titanium Dioxide Particle Type and Concentration Influence the Inflammatory Response in Caco-2 Cells.

    Science.gov (United States)

    Tada-Oikawa, Saeko; Ichihara, Gaku; Fukatsu, Hitomi; Shimanuki, Yuka; Tanaka, Natsuki; Watanabe, Eri; Suzuki, Yuka; Murakami, Masahiko; Izuoka, Kiyora; Chang, Jie; Wu, Wenting; Yamada, Yoshiji; Ichihara, Sahoko

    2016-04-16

    Titanium dioxide (TiO₂) nanoparticles are widely used in cosmetics, sunscreens, biomedicine, and food products. When used as a food additive, TiO₂ nanoparticles are used in significant amounts as white food-coloring agents. However, the effects of TiO₂ nanoparticles on the gastrointestinal tract remain unclear. The present study was designed to determine the effects of five TiO₂ particles of different crystal structures and sizes in human epithelial colorectal adenocarcinoma (Caco-2) cells and THP-1 monocyte-derived macrophages. Twenty-four-hour exposure to anatase (primary particle size: 50 and 100 nm) and rutile (50 nm) TiO₂ particles reduced cellular viability in a dose-dependent manner in THP-1 macrophages, but in not Caco-2 cells. However, 72-h exposure of Caco-2 cells to anatase (50 nm) TiO₂ particles reduced cellular viability in a dose-dependent manner. The highest dose (50 µg/mL) of anatase (100 nm), rutile (50 nm), and P25 TiO₂ particles also reduced cellular viability in Caco-2 cells. The production of reactive oxygen species tended to increase in both types of cells, irrespective of the type of TiO₂ particle. Exposure of THP-1 macrophages to 50 µg/mL of anatase (50 nm) TiO₂ particles increased interleukin (IL)-1β expression level, and exposure of Caco-2 cells to 50 µg/mL of anatase (50 nm) TiO₂ particles also increased IL-8 expression. The results indicated that anatase TiO₂ nanoparticles induced inflammatory responses compared with other TiO₂ particles. Further studies are required to determine the in vivo relevance of these findings to avoid the hazards of ingested particles.

  7. Titanium Dioxide Particle Type and Concentration Influence the Inflammatory Response in Caco-2 Cells

    Directory of Open Access Journals (Sweden)

    Saeko Tada-Oikawa

    2016-04-01

    Full Text Available Titanium dioxide (TiO2 nanoparticles are widely used in cosmetics, sunscreens, biomedicine, and food products. When used as a food additive, TiO2 nanoparticles are used in significant amounts as white food-coloring agents. However, the effects of TiO2 nanoparticles on the gastrointestinal tract remain unclear. The present study was designed to determine the effects of five TiO2 particles of different crystal structures and sizes in human epithelial colorectal adenocarcinoma (Caco-2 cells and THP-1 monocyte-derived macrophages. Twenty-four-hour exposure to anatase (primary particle size: 50 and 100 nm and rutile (50 nm TiO2 particles reduced cellular viability in a dose-dependent manner in THP-1 macrophages, but in not Caco-2 cells. However, 72-h exposure of Caco-2 cells to anatase (50 nm TiO2 particles reduced cellular viability in a dose-dependent manner. The highest dose (50 µg/mL of anatase (100 nm, rutile (50 nm, and P25 TiO2 particles also reduced cellular viability in Caco-2 cells. The production of reactive oxygen species tended to increase in both types of cells, irrespective of the type of TiO2 particle. Exposure of THP-1 macrophages to 50 µg/mL of anatase (50 nm TiO2 particles increased interleukin (IL-1β expression level, and exposure of Caco-2 cells to 50 µg/mL of anatase (50 nm TiO2 particles also increased IL-8 expression. The results indicated that anatase TiO2 nanoparticles induced inflammatory responses compared with other TiO2 particles. Further studies are required to determine the in vivo relevance of these findings to avoid the hazards of ingested particles.

  8. Clustering and preferential concentration of finite-size particles in forced homogeneous-isotropic turbulence

    CERN Document Server

    Uhlmann, Markus

    2016-01-01

    We have performed interface-resolved direct numerical simulations of forced homogeneous-isotropic turbulence in a dilute suspension of spherical particles in the Reynolds number range Re-lambda=115-140. The solid-fluid density ratio was set to 1.5, gravity was set to zero, and two particle diameters were investigated corresponding to approximately 5 and 11 Kolmogorov lengths. Note that these particle sizes are clearly outside the range of validity of the point-particle approximation, as has been shown by Homann & Bec (2010). At the present parameter points the global effect of the particles upon the fluid flow is weak. We observe that the dispersed phase exhibits clustering with moderate intensity. The tendency to cluster, which was quantified in terms of the standard deviation of Voronoi cell volumes, decreases with the particle diameter. We have analyzed the relation between particle locations and the location of intense vortical flow structures. The results do not reveal any significant statistical cor...

  9. Emulsion Polymerization of Etyl Acrylate: The Effect of Surfactant, Initiator Concentration and PolymerizationTechnique on Particle Size Distribution

    Directory of Open Access Journals (Sweden)

    Nitri Arinda

    2009-04-01

    Full Text Available Emulsion polymerization was conducted using ethyl acrylate monomer. Theeffect of sodium lauryl sulfate concentration, ammonium persulfate concentration, the various of polymerizationtechniques and feeding time to the conversion, particle size and its distribution were observed. The purpose of thisresearch is to obtain the optimum condition of ethyl acrylate homopolymer with particle size around 100 nm, to get theparticle size distribution monodisperse and to get solid content value of the experiment closed to its theoretical value.The optimum condition then could be applied in shell polymerization of core-shell polymers. The results of the researchshowed that semicontinuous technique obtained optimum sodium lauryl sulfate concentration at 20 CMC (criticalmicelle concentration and ammonium persulfate concentration is 3%. By using batch technique that the biggestparticle size is 123 nm with conversion 95.8% and monodisperse. The shorter of feeding time the more monomer ofethyl acrylate being polymerized, it is showed by the higher conversion up to 94.4% and the bigger particle size is107.9 nm.

  10. Influence of hydrogen concentration on Fe2O3 particle reduction in fluidized beds under constant drag force

    Institute of Scientific and Technical Information of China (English)

    Lei Guo; Han Gao; Jin-tao Yu; Zong-liang Zhang; Zhan-cheng Guo

    2015-01-01

    The fixed-gas drag force from a model calculation method that stabilizes the agitation capabilities of different gas ratios was used to explore the influence of temperature and hydrogen concentration on fluidizing duration, metallization ratio, utilization rate of reduction gas, and sticking behavior. Different hydrogen concentrations from 5vol%to 100vol%at 1073 and 1273 K were used while the drag force with the flow of N2 and H2 (N2:2 L·min−1;H2:2 L·min−1) at 1073 K was chosen as the standard drag force. The metallization ratio, mean reduc-tion rate, and utilization rate of reduction gas were observed to generally increase with increasing hydrogen concentration. Faster reduction rates and higher metallization ratios were obtained when the reduction temperature decreased from 1273 to 1073 K. A numerical relation among particle diameter, particle drag force, and fluidization state was plotted in a diagram by this model.

  11. Zone of influence for particle number concentrations at signalised traffic intersections

    Science.gov (United States)

    Goel, Anju; Kumar, Prashant

    2015-12-01

    Estimation of zone of influences (ZoI) at signalised traffic intersections (TI) is important to accurately model particle number concentrations (PNCs) and their exposure to public at emission hotspot locations. However, estimates of ZoI for PNCs at different types of TIs are barely known. We carried out mobile measurements inside the car cabin with windows fully open for size-resolved PNCs in the 5-560 nm range on a 6 km long busy round route that had 10 TIs. These included four-way TIs without built-up area (TI4w-nb), four-way TIs with built-up area (TI4w-wb), three-way TIs without built-up area (TI3w-nb) and three-way TIs with built-up area (TI3w-wb). Mobile measurements were made with a fast response differential mobility spectrometer (DMS50). Driving speed and position of the car were recorded every second using a global positioning system (GPS). Positive matrix factorisation (PMF) modelling was applied on the data to quantify the contribution of PNCs released during deceleration, creep-idling, acceleration and cruising to total PNCs at the TIs. The objectives were to address the following questions: (i) how does ZoI vary at different types of TIs in stop- and go-driving conditions?, (ii) what is the effect of different driving conditions on ZoI of a TI?, (iii) how realistically can the PNC profiles be generalised within a ZoI of a TI?, and (iv) what is the share of emissions during different driving conditions towards the total PNCs at a TI? Average length of ZoI in longitudinal direction and along the road was found to be the highest (148 m; 89 to -59 m from the centre of a TI) at a TI3w-wb, followed by TI4w-nb (129 m; 79 to -42 m), TI3w-nb (86 m; 71 to -15 m) and TI4w-wb (79 m; 46 to -33 m) in stop- and go-driving conditions. During multiple stopping driving conditions when a vehicle stops at a TI more than once in a signal cycle due to oversaturation of vehicles, average length of ZoI increased by 55, 22 and 21% at TI4w-nb, TI3w-nb and TI3w-wb, respectively

  12. Cardiopulmonary Toxicity Induced by Ambient Particulate Matter (BI City Concentrated Ambient Particle Study)

    Energy Technology Data Exchange (ETDEWEB)

    Annette Rohr; James Wagner Masako Morishita; Gerald Keeler; Jack Harkema

    2010-06-30

    Alterations in heart rate variability (HRV) have been reported in rodents exposed to concentrated ambient particles (CAPs) from different regions of the United States. The goal of this study was to compare alterations in cardiac function induced by CAPs in two distinct regional atmospheres. AirCARE 1, a mobile laboratory with an EPA/Harvard fine particle (particulate matter <2.5 {micro}m; PM{sub 2.5}) concentrator was located in urban Detroit, MI, where the PM mixture is heavily influenced by motor vehicles, and in Steubenville, OH, where PM is derived primarily from long-range transport and transformation of power plant emissions, as well as from local industrial operations. Each city was studied during both winter and summer months, for a total of four sampling periods. Spontaneously hypertensive rats instrumented for electrocardiogram (ECG) telemetry were exposed to CAPs 8 h/day for 13 consecutive days during each sampling period. Heart rate (HR), and indices of HRV (standard deviation of the average normal-to-normal intervals [SDNN]; square root of the mean squared difference of successive normal-to-normal intervals [rMSSD]), were calculated for 30-minute intervals during exposures. A large suite of PM components, including nitrate, sulfate, elemental and organic carbon, and trace elements, were monitored in CAPs and ambient air. In addition, a unique sampler, the Semi-Continuous Elements in Air Sampler (SEAS) was employed to obtain every-30-minute measurements of trace elements. Positive matrix factorization (PMF) methods were applied to estimate source contributions to PM{sub 2.5}. Mixed modeling techniques were employed to determine associations between pollutants/CAPs components and HR and HRV metrics. Mean CAPs concentrations in Detroit were 518 and 357 {micro}g/m{sup 3} (summer and winter, respectively) and 487 and 252 {micro}g/m{sup 3} in Steubenville. In Detroit, significant reductions in SDNN were observed in the summer in association with cement

  13. Cardiopulmonary Toxicity Induced by Ambient Particulate Matter (BI City Concentrated Ambient Particle Study)

    Energy Technology Data Exchange (ETDEWEB)

    Annette Rohr; James Wagner Masako Morishita; Gerald Keeler; Jack Harkema

    2010-06-30

    Alterations in heart rate variability (HRV) have been reported in rodents exposed to concentrated ambient particles (CAPs) from different regions of the United States. The goal of this study was to compare alterations in cardiac function induced by CAPs in two distinct regional atmospheres. AirCARE 1, a mobile laboratory with an EPA/Harvard fine particle (particulate matter <2.5 {micro}m; PM{sub 2.5}) concentrator was located in urban Detroit, MI, where the PM mixture is heavily influenced by motor vehicles, and in Steubenville, OH, where PM is derived primarily from long-range transport and transformation of power plant emissions, as well as from local industrial operations. Each city was studied during both winter and summer months, for a total of four sampling periods. Spontaneously hypertensive rats instrumented for electrocardiogram (ECG) telemetry were exposed to CAPs 8 h/day for 13 consecutive days during each sampling period. Heart rate (HR), and indices of HRV (standard deviation of the average normal-to-normal intervals [SDNN]; square root of the mean squared difference of successive normal-to-normal intervals [rMSSD]), were calculated for 30-minute intervals during exposures. A large suite of PM components, including nitrate, sulfate, elemental and organic carbon, and trace elements, were monitored in CAPs and ambient air. In addition, a unique sampler, the Semi-Continuous Elements in Air Sampler (SEAS) was employed to obtain every-30-minute measurements of trace elements. Positive matrix factorization (PMF) methods were applied to estimate source contributions to PM{sub 2.5}. Mixed modeling techniques were employed to determine associations between pollutants/CAPs components and HR and HRV metrics. Mean CAPs concentrations in Detroit were 518 and 357 {micro}g/m{sup 3} (summer and winter, respectively) and 487 and 252 {micro}g/m{sup 3} in Steubenville. In Detroit, significant reductions in SDNN were observed in the summer in association with cement

  14. Effect of particle size and temperature on rheology and creep behavior of barley β-d-glucan concentrate dough.

    Science.gov (United States)

    Ahmed, Jasim

    2014-10-13

    Concentrated β-D-glucan has been added in the formulation of food products development that attributing human health. The purpose of this study is to assess the role of particle size (74, 105, 149, 297 and 595 μm) of barley β-D-glucan concentrate (BGC) on two fundamental rheological properties namely oscillatory rheology and creep in a dough system (sample to water = 1:2). The water holding capacity, sediment volume fraction and protein content increased with an increase in particle size from 74 μm to 595 μm, which directly influences the mechanical strength and visco-elasticity of the dough. The dough exhibited predominating solid-like behavior (elastic modulus, G'>viscous modulus, G"). The G' decreased systematically with increasing temperature from 25 to 85 °C at the frequency range of 0.1-10 Hz except for the dough having particle size of 105 μm, which could be associated with increase in protein content in the fraction. A discrete retardation spectrum is employed to the creep data to obtain retardation time and compliance parameters which varied significantly with particle size and the process temperature. All those information could be helpful to identify the particle size range of BGC that could be useful to produce a β-D-glucan enriched designed food.

  15. Protoplanetary Disk Turbulence Driven by the Streaming Instability: Non-Linear Saturation and Particle Concentration

    CERN Document Server

    Johansen, A; Johansen, Anders; Youdin, Andrew

    2007-01-01

    We present simulations of the non-linear evolution of streaming instabilities in protoplanetary disks. The two components of the disk, gas treated with grid hydrodynamics and solids treated as superparticles, are mutually coupled by drag forces. We find that the initially laminar equilibrium flow spontaneously develops into turbulence in our unstratified local model. Marginally coupled solids (that couple to the gas on a Keplerian time-scale) trigger an upward cascade to large particle clumps with peak overdensities above 100. The clumps evolve dynamically by losing material downstream to the radial drift flow while receiving recycled material from upstream. Smaller, more tightly coupled solids produce weaker turbulence with more transient overdensities on smaller length scales. The net inward radial drift is decreased for marginally coupled particles, whereas the tightly coupled particles migrate faster in the saturated turbulent state. The turbulent diffusion of solid particles, measured by their random wal...

  16. Effect of Aerogel Particle Concentration on Mechanical Behavior of Impregnated RTV 655 Compound Material for Aerospace Applications

    Directory of Open Access Journals (Sweden)

    Firouzeh Sabri

    2014-01-01

    Full Text Available Aerogels are a unique class of materials with superior thermal and mechanical properties particularly suitable for insulating and cryogenic storage applications. It is possible to overcome geometrical restrictions imposed by the rigidity of monolithic polyurea cross-linked silica aerogels by encapsulating micrometer-sized particles in a chemically resistant thermally insulating elastomeric “sleeve.” The ultimate limiting factor for the compound material’s performance is the effect of aerogel particles on the mechanical behavior of the compound material which needs to be fully characterized. The effect of size and concentration of aerogel microparticles on the tensile behavior of aerogel impregnated RTV655 samples was explored both at room temperature and at 77 K. Aerogel microparticles were created using a step-pulse pulverizing technique resulting in particle diameters between 425 μm and 90 μm and subsequently embedded in an RTV 655 elastomeric matrix. Aerogel particle concentrations of 25, 50, and 75 wt% were subjected to tensile tests and behavior of the compound material was investigated. Room temperature and cryogenic temperature studies revealed a compound material with rupture load values dependent on (1 microparticle size and (2 microparticle concentration. Results presented show how the stress elongation behavior depends on each parameter.

  17. Cascading and Parallelising Curvilinear Inertial Focusing Systems for High Volume, Wide Size Distribution, Separation and Concentration of Particles

    Science.gov (United States)

    Miller, B.; Jimenez, M.; Bridle, H.

    2016-11-01

    Inertial focusing is a microfluidic based separation and concentration technology that has expanded rapidly in the last few years. Throughput is high compared to other microfluidic approaches although sample volumes have typically remained in the millilitre range. Here we present a strategy for achieving rapid high volume processing with stacked and cascaded inertial focusing systems, allowing for separation and concentration of particles with a large size range, demonstrated here from 30 μm-300 μm. The system is based on curved channels, in a novel toroidal configuration and a stack of 20 devices has been shown to operate at 1 L/min. Recirculation allows for efficient removal of large particles whereas a cascading strategy enables sequential removal of particles down to a final stage where the target particle size can be concentrated. The demonstration of curved stacked channels operating in a cascaded manner allows for high throughput applications, potentially replacing filtration in applications such as environmental monitoring, industrial cleaning processes, biomedical and bioprocessing and many more.

  18. Short-term overexpression of DGAT1 or DGAT2 increases hepatic triglyceride but not VLDL triglyceride or apoB production

    NARCIS (Netherlands)

    Millar, John S.; Stone, Scot J.; Tietge, Uwe J. F.; Tow, Bryan; Billheimer, Jeffrey T.; Wong, Jinny S.; Hamilton, Robert L.; Farese, Robert V.; Rader, Daniel J.

    2006-01-01

    Increased triglyceride synthesis resulting from enhanced flux of fatty acids into liver is frequently associated with VLDL overproduction. This has led to the common belief that hepatic triglyceride synthesis can directly modulate VLDL production. We used adenoviral vectors containing either murine

  19. Spontaneous concentrations of solids through two-way drag forces between gas and sedimenting particles

    CERN Document Server

    Lambrechts, Michiel; Capelo, Holly L; Blum, Jürgen; Bodenschatz, Eberhard

    2016-01-01

    The behaviour of sedimenting particles depends on the dust-to-gas ratio of the fluid. Linear stability analysis shows that solids settling in the Epstein drag regime would remain homogeneously distributed in non-rotating incompressible fluids, even when dust-to-gas ratios reach unity. However, the non-linear evolution has not been probed before. Here, we present numerical calculations indicating that in a particle-dense mixture solids spontaneously mix out of the fluid and form swarms overdense in particles by at least a factor 10. The instability is caused by mass-loaded regions locally breaking the equilibrium background stratification. The driving mechanism depends on non-linear perturbations of the background flow and shares some similarity to the streaming instability in accretion discs. The resulting particle-rich swarms may stimulate particle growth by coagulation. In the context of protoplanetary discs, the instability could be relevant for aiding small particles to settle to the midplane in the outer...

  20. Flow speed alters the apparent size and concentration of particles measured using NanoSight nanoparticle tracking analysis.

    Science.gov (United States)

    Tong, M; Brown, O S; Stone, P R; Cree, L M; Chamley, L W

    2016-02-01

    Nanoparticle tracking analysis (NTA) is commonly used to count and size nano-sized particles. A sample loading pump can be used to analyse a larger sample volume, but it is unclear whether accuracy is affected. Using a NanoSight NS300 with the manufacturer-supplied pump, we examined synthetic silica and latex microspheres, liposomes and placental extracellular vesicles at different flow speeds. Analysis at flow speeds of 20 or 50 significantly reduced the measured concentration and mean/modal size of particles, particularly for mono-dispersed samples. We identify sample flow speed as a crucial instrument setting which should be reported in all studies that use NTA.

  1. Assessment of large-eddy simulation in capturing preferential concentration of heavy particles in isotropic turbulent flows

    Science.gov (United States)

    Jin, Guodong; Zhang, Jian; He, Guo-Wei; Wang, Lian-Ping

    2010-12-01

    Particle-laden turbulent flow is a typical non-equilibrium process characterized by particle relaxation time τp and the characteristic timescale of the flows τf, in which the turbulent mixing of heavy particles is related to different scales of fluid motions. The preferential concentration (PC) of heavy particles could be strongly affected by fluid motion at dissipation-range scales, which presents a major challenge to the large-eddy simulation (LES) approach. The errors in simulated PC by LES are due to both filtering and the subgrid scale (SGS) eddy viscosity model. The former leads to the removal of the SGS motion and the latter usually results in a more spatiotemporally correlated vorticity field. The dependence of these two factors on the flow Reynolds number is assessed using a priori and a posteriori tests, respectively. The results suggest that filtering is the dominant factor for the under-prediction of the PC for Stokes numbers less than 1, while the SGS eddy viscosity model is the dominant factor for the over-prediction of the PC for Stokes numbers between 1 and 10. The effects of the SGS eddy viscosity model on the PC decrease as the Reynolds number and Stokes number increase. LES can well predict the PC for particle Stokes numbers larger than 10. An SGS model for particles with small and intermediate Stokes numbers is needed to account for the effects of the removed SGS turbulent motion on the PC.

  2. Assessment of large-eddy simulation in capturing preferential concentration of heavy particles in isotropic turbulent flows

    Energy Technology Data Exchange (ETDEWEB)

    Jin Guodong; Zhang Jian; He Guowei; Wang Lianping, E-mail: hgw@lnm.imech.ac.cn [LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

    2010-12-15

    Particle-laden turbulent flow is a typical non-equilibrium process characterized by particle relaxation time {tau}{sub p} and the characteristic timescale of the flows {tau}{sub f}, in which the turbulent mixing of heavy particles is related to different scales of fluid motions. The preferential concentration (PC) of heavy particles could be strongly affected by fluid motion at dissipation-range scales, which presents a major challenge to the large-eddy simulation (LES) approach. The errors in simulated PC by LES are due to both filtering and the subgrid scale (SGS) eddy viscosity model. The former leads to the removal of the SGS motion and the latter usually results in a more spatiotemporally correlated vorticity field. The dependence of these two factors on the flow Reynolds number is assessed using a priori and a posteriori tests, respectively. The results suggest that filtering is the dominant factor for the under-prediction of the PC for Stokes numbers less than 1, while the SGS eddy viscosity model is the dominant factor for the over-prediction of the PC for Stokes numbers between 1 and 10. The effects of the SGS eddy viscosity model on the PC decrease as the Reynolds number and Stokes number increase. LES can well predict the PC for particle Stokes numbers larger than 10. An SGS model for particles with small and intermediate Stokes numbers is needed to account for the effects of the removed SGS turbulent motion on the PC.

  3. Characterisation of sub-micron particle number concentrations and formation events in the western Bushveld Igneous Complex, South Africa

    Directory of Open Access Journals (Sweden)

    A. Hirsikko

    2012-05-01

    Full Text Available South Africa holds significant mineral resources, with a substantial fraction of these reserves occurring and being processed in a large geological structure termed the Bushveld Igneous Complex (BIC. The area is also highly populated by informal, semi-formal and formal residential developments. However, knowledge of air quality and research related to the atmosphere is still very limited in the area. In order to investigate the characteristics and processes affecting sub-micron particle number concentrations and formation events, air ion and aerosol particle size distributions and number concentrations, together with meteorological parameters, trace gases and particulate matter (PM were measured for over two years at Marikana in the heart of the western BIC. The observations showed that trace gas (i.e. SO2, NOx, CO and black carbon concentrations were relatively high, but in general within the limits of local air quality standards. The area was characterised by very high condensation sink due to background aerosol particles, PM10 and O3 concentration. The results indicated that high amounts of Aitken and accumulation mode particles originated from domestic burning for heating and cooking in the morning and evening, while during daytime SO2-based nucleation followed by the growth by condensation of vapours from industrial, residential and natural sources was the most probable source for large number concentrations of nucleation and Aitken mode particles. Nucleation event day frequency was extremely high, i.e. 86% of the analysed days, which to the knowledge of the authors is the highest frequency ever reported. The air mass back trajectory and wind direction analyses showed that the secondary particle formation was influenced both by local and regional pollution and vapour sources. Therefore, our observation of the annual cycle and magnitude of the particle formation and growth rates during

  4. Reduction of VLDL secretion decreases cholesterol excretion in niemann-pick C1-like 1 hepatic transgenic mice.

    Directory of Open Access Journals (Sweden)

    Stephanie M Marshall

    Full Text Available An effective way to reduce LDL cholesterol, the primary risk factor of atherosclerotic cardiovascular disease, is to increase cholesterol excretion from the body. Our group and others have recently found that cholesterol excretion can be facilitated by both hepatobiliary and transintestinal pathways. However, the lipoprotein that moves cholesterol through the plasma to the small intestine for transintestinal cholesterol efflux (TICE is unknown. To test the hypothesis that hepatic very low-density lipoproteins (VLDL support TICE, antisense oligonucleotides (ASO were used to knockdown hepatic expression of microsomal triglyceride transfer protein (MTP, which is necessary for VLDL assembly. While maintained on a high cholesterol diet, Niemann-Pick C1-like 1 hepatic transgenic (L1Tg mice, which predominantly excrete cholesterol via TICE, and wild type (WT littermates were treated with control ASO or MTP ASO. In both WT and L1Tg mice, MTP ASO decreased VLDL triglyceride (TG and cholesterol secretion. Regardless of treatment, L1Tg mice had reduced biliary cholesterol compared to WT mice. However, only L1Tg mice treated with MTP ASO had reduced fecal cholesterol excretion. Based upon these findings, we conclude that VLDL or a byproduct such as LDL can move cholesterol from the liver to the small intestine for TICE.

  5. Hepatocyte-specific IKK-β activation enhances VLDL-triglyceride production in APOE*3-Leiden mice.

    Science.gov (United States)

    van Diepen, Janna A; Wong, Man C; Guigas, Bruno; Bos, Jasper; Stienstra, Rinke; Hodson, Leanne; Shoelson, Steven E; Berbée, Jimmy F P; Rensen, Patrick C N; Romijn, Johannes A; Havekes, Louis M; Voshol, Peter J

    2011-05-01

    Low-grade inflammation in different tissues, including activation of the nuclear factor κB pathway in liver, is involved in metabolic disorders such as type 2 diabetes and cardiovascular diseases (CVDs). In this study, we investigated the relation between chronic hepatocyte-specific overexpression of IkB kinase (IKK)-β and hypertriglyceridemia, an important risk factor for CVD, by evaluating whether activation of IKK-β only in the hepatocyte affects VLDL-triglyceride (TG) metabolism directly. Transgenic overexpression of constitutively active human IKK-β specifically in hepatocytes of hyperlipidemic APOE*3-Leiden mice clearly induced hypertriglyceridemia. Mechanistic in vivo studies revealed that the hypertriglyceridemia was caused by increased hepatic VLDL-TG production rather than a change in plasma VLDL-TG clearance. Studies in primary hepatocytes showed that IKK-β overexpression also enhances TG secretion in vitro, indicating a direct relation between IKK-β activation and TG production within the hepatocyte. Hepatic lipid analysis and hepatic gene expression analysis of pathways involved in lipid metabolism suggested that hepatocyte-specific IKK-β overexpression increases VLDL production not by increased steatosis or decreased FA oxidation, but most likely by carbohydrate-responsive element binding protein-mediated upregulation of Fas expression. These findings implicate that specific activation of inflammatory pathways exclusively within hepatocytes induces hypertriglyceridemia. Furthermore, we identify the hepatocytic IKK-β pathway as a possible target to treat hypertriglyceridemia.

  6. Lipoprotein lipase S447X variant associated with VLDL, LDL and HDL diameter clustering in the MetS

    Science.gov (United States)

    Previous analysis clustered 1,238 individuals from the general population Genetics of Lipid Lowering Drugs Network (GOLDN) study by the size of their fasting very low-density, low-density and high-density lipoproteins (VLDL, LDL, HDL) using latent class analysis. From two of the eight identified gro...

  7. Effects of dietary fish oil on serum lipids and VLDL kinetics in hyperlipidemic apolipoprotein E*3-Leiden transgenic mice

    NARCIS (Netherlands)

    Vlijmen, B.J.M. van; Mensink, R.P.; Hof, H.B. van 't; Offermans, R.F.G.; Hofker, M.H.; Havekes, L.M.

    1998-01-01

    Studying the effects of dietary fish oil on VLDL metabolism in humans is subject to both large intra- and interindividual variability. In the present study we therefore used hyperlipidentic apolipoprotein (APO) E*3-Leiden mice, which have impaired chylomicron and very low density lipoprotein (VDL) r

  8. Increased VLDL in nephrotic patients results from a decreased catabolism while increased LDL results from increased synthesis

    NARCIS (Netherlands)

    de Sain-van der Velden, M; Kaysen, GA; Barrett, HA; Stellaard, F; Gadellaa, MM; Voorbij, HA; Reijngoud, DJ; Rabelink, TJ

    1998-01-01

    Increased very low density lipoprotein (VLDL) in nephrotic patients results from a decreased catabolism while increased low density lipoprotein (LDL) results from increased synthesis. Hyperlipidemias a hallmark of nephrotic syndrome that has been associated with increased risk for ischemic heart dis

  9. Reduction of VLDL secretion decreases cholesterol excretion in niemann-pick C1-like 1 hepatic transgenic mice.

    Science.gov (United States)

    Marshall, Stephanie M; Kelley, Kathryn L; Davis, Matthew A; Wilson, Martha D; McDaniel, Allison L; Lee, Richard G; Crooke, Rosanne M; Graham, Mark J; Rudel, Lawrence L; Brown, J Mark; Temel, Ryan E

    2014-01-01

    An effective way to reduce LDL cholesterol, the primary risk factor of atherosclerotic cardiovascular disease, is to increase cholesterol excretion from the body. Our group and others have recently found that cholesterol excretion can be facilitated by both hepatobiliary and transintestinal pathways. However, the lipoprotein that moves cholesterol through the plasma to the small intestine for transintestinal cholesterol efflux (TICE) is unknown. To test the hypothesis that hepatic very low-density lipoproteins (VLDL) support TICE, antisense oligonucleotides (ASO) were used to knockdown hepatic expression of microsomal triglyceride transfer protein (MTP), which is necessary for VLDL assembly. While maintained on a high cholesterol diet, Niemann-Pick C1-like 1 hepatic transgenic (L1Tg) mice, which predominantly excrete cholesterol via TICE, and wild type (WT) littermates were treated with control ASO or MTP ASO. In both WT and L1Tg mice, MTP ASO decreased VLDL triglyceride (TG) and cholesterol secretion. Regardless of treatment, L1Tg mice had reduced biliary cholesterol compared to WT mice. However, only L1Tg mice treated with MTP ASO had reduced fecal cholesterol excretion. Based upon these findings, we conclude that VLDL or a byproduct such as LDL can move cholesterol from the liver to the small intestine for TICE.

  10. Simulated tritium concentrations in river waters of the western Lake Taupo catchment, New Zealand with MODPATH particle tracking

    Directory of Open Access Journals (Sweden)

    M. A. Gusyev

    2014-03-01

    Full Text Available We simulated in a previous study tritium concentrations in the river waters of the western Lake Taupo catchment (WLTC using MODFLOW/MT3DMS model (Gusyev et al., 2013. The model was calibrated to match simulated tritium to measured tritium in river waters at baseflows of the Waihaha, Whanganui, Whareroa, Kuratau and Omori river catchments of the WLTC. Following from this work we now utilized the same MODFLOW model for the WLTC to calculate the pathways of groundwater particles (and their corresponding tritium concentrations using steady-state particle tracking with MODPATH. In order to simulate baseflow tritium concentrations with MODPATH, transit time distributions (TTDs such as cumulative frequency distribution (CFD and probability density function (PDF are generated with particle tracking for the river networks of the five WLTC catchment outflows. Then, PDFs are used in the convolution integral with tritium concentration time series obtained in the precipitation. The resulting MODPATH tritium concentrations yield a very good match to measured tritium concentrations and are similar to the MT3DMS simulated tritium concentrations, with the greatest variation occurring around the bomb peak. MODPATH and MT3DMS also yield similar Mean Transit Times (MTT of groundwater contribution to river baseflows, but the actual shape of the TTDs is strikingly different. While both distributions provide valuable information, the methodologies used to derive the TTDs are fundamentally different and hence must be interpreted differently. With the current models setting, only the methodology used with MODPATH provides the true TTD for use with the convolution integral.

  11. Fluorescent bioaerosol particle, molecular tracer, and fungal spore concentrations during dry and rainy periods in a semi-arid forest

    Science.gov (United States)

    Ila Gosselin, Marie; Rathnayake, Chathurika M.; Crawford, Ian; Pöhlker, Christopher; Fröhlich-Nowoisky, Janine; Schmer, Beatrice; Després, Viviane R.; Engling, Guenter; Gallagher, Martin; Stone, Elizabeth; Pöschl, Ulrich; Huffman, J. Alex

    2016-12-01

    Bioaerosols pose risks to human health and agriculture and may influence the evolution of mixed-phase clouds and the hydrological cycle on local and regional scales. The availability and reliability of methods and data on the abundance and properties of atmospheric bioaerosols, however, are rather limited. Here we analyze and compare data from different real-time ultraviolet laser/light-induced fluorescence (UV-LIF) instruments with results from a culture-based spore sampler and offline molecular tracers for airborne fungal spores in a semi-arid forest in the southern Rocky Mountains of Colorado. Commercial UV-APS (ultraviolet aerodynamic particle sizer) and WIBS-3 (wideband integrated bioaerosol sensor, version 3) instruments with different excitation and emission wavelengths were utilized to measure fluorescent aerosol particles (FAPs) during both dry weather conditions and periods heavily influenced by rain. Seven molecular tracers of bioaerosols were quantified by analysis of total suspended particle (TSP) high-volume filter samples using a high-performance anion-exchange chromatography system with pulsed amperometric detection (HPAEC-PAD). From the same measurement campaign, Huffman et al. (2013) previously reported dramatic increases in total and fluorescent particle concentrations during and immediately after rainfall and also showed a strong relationship between the concentrations of FAPs and ice nuclei (Huffman et al., 2013; Prenni et al., 2013). Here we investigate molecular tracers and show that during rainy periods the atmospheric concentrations of arabitol (35.2 ± 10.5 ng m-3) and mannitol (44.9 ± 13.8 ng m-3) were 3-4 times higher than during dry periods. During and after rain, the correlations between FAP and tracer mass concentrations were also significantly improved. Fungal spore number concentrations on the order of 104 m-3, accounting for 2-5 % of TSP mass during dry periods and 17-23 % during rainy periods, were obtained from scaling the

  12. Susceptibility of Tribolium confusum (Coleoptera: Tenebrionidae) to Pyrethrin Aerosol: Effects of Aerosol Particle Size, Concentration, and Exposure Conditions.

    Science.gov (United States)

    Arthur, Frank H; Campbell, James F; Ducatte, Gerald R

    2014-12-01

    A series of laboratory studies was conducted to assess the effect of droplet size on efficacy of pyrethrin aerosol against adults of Tribolium confusum Jacqueline DuVal, the confused flour beetle. A vertical flow aerosol exposure chamber that generated a standardized particle size diameter was used for these trials. In the first experiments, adults were exposed in the chamber for 2.5-45 min to aerosol dispensed at a volumetric median particle size diameter (VMD) of 16 μm, and then held in the arenas in which they were exposed or transferred to new arenas with or without a flour food source. All adults were initially knocked down when removed from the chamber. Recovery from knockdown decreased as exposure interval increased, but the presence of a food source enhanced recovery at the lower exposure intervals. In the second experiment, the aerosol was applied at a VMD of 2 μm and adults were exposed for between 5 and 75 min. Knockdown of adults was ≤10% when adults were removed from the chamber regardless of exposure time and afterward there was essentially complete recovery of adults. In the third and final experiment, the same 2-μm VMD particle size and exposure times were used, but the concentration of aerosol was increased by ≍4× compared with the previous experiment. In this test, initial knockdown was greater at the higher exposure intervals, but by 3 and 4 d posttreatment, recovery was again essentially 100%. This is the first published test assessing the efficacy of specific aerosol particle sizes on a stored product insect. Results indicate that particle size was a more important factor in conferring toxicity than the actual concentration or number of aerosol particles. © 2014 Entomological Society of America.

  13. Improved concentration and separation of particles in a 3D dielectrophoretic chip integrating focusing, aligning and trapping

    KAUST Repository

    Li, Ming

    2012-10-18

    This article presents a dielectrophoresis (DEP)-based microfluidic device with the three-dimensional (3D) microelectrode configuration for concentrating and separating particles in a continuous throughflow. The 3D electrode structure, where microelectrode array are patterned on both the top and bottom surfaces of the microchannel, is composed of three units: focusing, aligning and trapping. As particles flowing through the microfluidic channel, they are firstly focused and aligned by the funnel-shaped and parallel electrode array, respectively, before being captured at the trapping unit due to negative DEP force. For a mixture of two particle populations of different sizes or dielectric properties, with a careful selection of suspending medium and applied field, the population exhibits stronger negative DEP manipulated by the microelectrode array and, therefore, separated from the other population which is easily carried away toward the outlet due to hydrodynamic force. The functionality of the proposed microdevice was verified by concentrating different-sized polystyrene (PS) microparticles and yeast cells dynamically flowing in the microchannel. Moreover, separation based on size and dielectric properties was achieved by sorting PS microparticles, and isolating 5 μm PS particles from yeast cells, respectively. The performance of the proposed micro-concentrator and separator was also studied, including the threshold voltage at which particles begin to be trapped, variation of cell-trapping efficiency with respect to the applied voltage and flow rate, and the efficiency of separation experiments. The proposed microdevice has various advantages, including multi-functionality, improved manipulation efficiency and throughput, easy fabrication and operation, etc., which shows a great potential for biological, chemical and medical applications. © 2012 Springer-Verlag Berlin Heidelberg.

  14. Evaluation of number concentration quantification by single-particle inductively coupled plasma mass spectrometry: microsecond vs. millisecond dwell times.

    Science.gov (United States)

    Abad-Álvaro, Isabel; Peña-Vázquez, Elena; Bolea, Eduardo; Bermejo-Barrera, Pilar; Castillo, Juan R; Laborda, Francisco

    2016-07-01

    The quality of the quantitative information in single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS) depends directly on the number concentration of the nanoparticles in the sample analyzed, which is proportional to the flux of nanoparticles through the plasma. Particle number concentrations must be selected in accordance with the data acquisition frequency, to control the precision from counting statistics and the bias, which is produced by the occurrence of multiple-particle events recorded as single-particle events. With quadrupole mass spectrometers, the frequency of data acquisition is directly controlled by the dwell time. The effect of dwell times from milli- to microseconds (10 ms, 5 ms, 100 μs, and 50 μs) on the quality of the quantitative data has been studied. Working with dwell times in the millisecond range, precision figures about 5 % were achieved, whereas using microsecond dwell times, the suitable fluxes of nanoparticles are higher and precision was reduced down to 1 %; this was independent of the dwell time selected. Moreover, due to the lower occurrence of multiple-nanoparticle events, linear ranges are wider when dwell times equal to or shorter than 100 μs are used. A calculation tool is provided to determine the optimal concentration for any instrument or experimental conditions selected. On the other hand, the use of dwell times in the microsecond range reduces significantly the contribution of the background and/or the presence of dissolved species, in comparison with the use of millisecond dwell times. Although the use of dwell times equal to or shorter than 100 μs offers improved performance working in single-particle mode, the use of conventional dwell times (3-10 ms) should not be discarded, once their limitations are known.

  15. Frequency-dependent electrical conductivity of concentrated dispersions of spherical colloidal particles.

    Science.gov (United States)

    Bradshaw-Hajek, B H; Miklavcic, S J; White, L R

    2008-05-06

    This paper outlines the application of a self-consistent cell-model theory of electrokinetics to the problem of determining the electrical conductivity of a dense suspension of spherical colloidal particles. Numerical solutions of the standard electrokinetic equations, subject to self-consistent boundary conditions, are implemented in formulas for the electrical conductivity appropriate to the particle-averaged cell model of the suspension. Results of calculations as a function of frequency, zeta potential, volume fraction, and electrolyte composition, are presented and discussed.

  16. Adsorption and stabilization of nano-TiO2 particles in a concentrated dispersion

    Institute of Scientific and Technical Information of China (English)

    Fuchun Liun; En-Hou Han; Wei Ke

    2013-01-01

    The quantitative adsorption behavior of a hyperdispersant onto nano-TiO2 particles has been characterized by using FTIR (Fourier transform infrared) spectroscopy, NMR (nuclear magnetic resonance) and a negative adsorption method. The intrinsic adsorbed amount of hyperdispersant was (1.0570.09) mg/m2. Thickness of the adsorbed layer was (4.6670.42) nm. There was (7477)%wt water in the adsorbed layer. In the hyperdispersant molecule, the anchoring group of the amide group attached firmly to the nano-TiO2 particles, and the solvatable chains of comb-type structure exhibited the effective steric stabilization.

  17. Influence of particle size and concentration on the diffuse backscattering of polarized light from tissue phantoms and biological cell suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Hielscher, A.H.; Mourant, J.R.; Bigio, I.J. [Los Alamos National Laboratory, Bioscience and Biotechnology, CST-4, MS E535, Los Alamos, New Mexico 87545 (United States)

    1997-01-01

    We present experimental results that show the spatial variations of the diffuse-backscattered intensity when linearly polarized light is incident upon highly scattering media. Experiments on polystyrene-sphere and Intralipid suspensions demonstrate that the radial and azimuthal variations of the observed pattern depend on the concentration, and anisotropy factor {ital g} of the particles that constitute the scattering medium. Measurements performed on biological-cell suspensions show the potential of this method for cell characterization. {copyright} 1997 Optical Society of America

  18. Tethered balloon-based particle number concentration, and size distribution vertical profiles within the lower troposphere of Shanghai

    Science.gov (United States)

    Zhang, Kun; Wang, Dongfang; Bian, Qinggen; Duan, Yusen; Zhao, Mengfei; Fei, Dongnian; Xiu, Guangli; Fu, Qingyan

    2017-04-01

    A tethered balloon-based measurement campaign of particle number concentration (PNC) and particle number size distribution (PNSD) in the size range of 15.7-661.2 nm was conducted within the lower troposphere of 1000 m in Shanghai, a Chinese megacity, during December of 2015. The meteorological conditions, PNC, and PNSD were synchronously measured at the ground-based station as well as by the tethered balloon. On ground level, the 88.2 nm particles were found to have the highest PNC. The Pearson correlation analysis based on the ground level data showed NO2 had a strong correlation with PNC. The synchronous measurement of PNC and PNSD at the ground station and on the tethered balloon showed that the 15.7-200 nm particles had higher PNC on ground level, but the PNC of 200-661.2 nm particles was higher at 400 m. One haze event (Dec 22nd-Dec 23rd) was selected for detailed discussion on the variation of vertical profiles of PNSD and PNC. The vertical distribution of characteristics of PNC and PNSD were observed and compared. Results indicated that the highest MaxDm (the diameter with the highest PNC) during those three launches all appeared at a high altitude, usually above 300 m. Compared to the clean days, the relatively bigger MaxDm at each height in the haze days also indicated regional transport of pollutants might contribute to more to that haze event.

  19. Influence of trans-boundary biomass burning impacted air masses on submicron particle number concentrations and size distributions

    Science.gov (United States)

    Betha, Raghu; Zhang, Zhe; Balasubramanian, Rajasekhar

    2014-08-01

    Submicron particle number concentration (PNC) and particle size distribution (PSD) in the size range of 5.6-560 nm were investigated in Singapore from 27 June 2009 through 6 September 2009. Slightly hazy conditions lasted in Singapore from 6 to 10 August. Backward air trajectories indicated that the haze was due to the transport of biomass burning impacted air masses originating from wild forest and peat fires in Sumatra, Indonesia. Three distinct peaks in the morning (08:00-10:00), afternoon (13:00-15:00) and evening (16:00-20:00) were observed on a typical normal day. However, during the haze period no distinct morning and afternoon peaks were observed and the PNC (39,775 ± 3741 cm-3) increased by 1.5 times when compared to that during non-haze periods (26,462 ± 6017). The morning and afternoon peaks on the normal day were associated with the local rush hour traffic while the afternoon peak was induced by new particle formation (NPF). Diurnal profiles of PNCs and PSDs showed that primary particle peak diameters were large during the haze (60 nm) period when compared to that during the non-haze period (45.3 nm). NPF events observed in the afternoon period on normal days were suppressed during the haze periods due to heavy particle loading in atmosphere caused by biomass burning impacted air masses.

  20. The separation efficiency of ceramic barrier filters determined at high temperatures by optical particle size and concentration measurement

    Energy Technology Data Exchange (ETDEWEB)

    Hemmer, G.; Umhauer, H.; Kasper, G. [Univ. Karlsruhe, Inst. fuer Mechanische Verfahrenstechnik und Mechanik, Karlsruhe (Germany); Berbner, S. [Freudenberg Nonwovens, Filtration Div., Hopkinsville, KY (United States)

    1999-07-01

    Based on the experiences of earlier investigations a special optical particle counter was developed capable of recording size and quantity (concentration) of the particles directly within a given gas particle stream under the prevailing conditions (true in-situ measurements at high temperatures). In addition to earlier investigations [1], a second type of ceramic filter media with much smaller porosity and a membrane layer on the filtration side was tested. The candles with a length of 1.5 m which are used in industrial applications were mounted in the same hot gas filtration unit already used before. Measurements on the clean gas side at temperatures of up to 1000 C have been conducted using a fraction of quartz particles as test dust. The particle size ranged between 0.3 {mu}m and 10 {mu}m. Filtration velocity (1.5 cm/s) and final pressure drop of dust cake {delta}p (1000 Pa) were kept constant. As a main result the fractional efficiency as function of temperature is discussed and compared with that obtained before for a filter media of type I: The fractional efficiency values of filter type II are at least 100 times higher than that of filter type I. (orig.)

  1. Vascular Effects of a Subchronic Inhalation Exposure to Concentrated Ambient Air Particles in Atherosclerosis Susceptible Mice

    Science.gov (United States)

    Numerous studies have reported the adverse effects of particulate air pollution on cardiovascular function and disease. The causal physiochemical properties of particles and their mechanisms of action/injury remain unknown. This study examined the vascular effects in 15 wk old ma...

  2. Optical tweezers in concentrated colloidal dispersions : Manipulating and imaging individual particles

    NARCIS (Netherlands)

    Vossen, Dirk Leo Joep

    2004-01-01

    Using a laser beam that is focused down to a diffraction-limited spot, particles with a size ranging from several nanometers up to tens of micrometers can be trapped and manipulated. This technique, known as "optical tweezers" or "optical trapping", has been used in a wide variety of (interdisciplin

  3. Optical tweezers in concentrated colloidal dispersions : Manipulating and imaging individual particles

    NARCIS (Netherlands)

    Vossen, Dirk Leo Joep

    2004-01-01

    Using a laser beam that is focused down to a diffraction-limited spot, particles with a size ranging from several nanometers up to tens of micrometers can be trapped and manipulated. This technique, known as "optical tweezers" or "optical trapping", has been used in a wide variety of

  4. Effects of locust bean gum and mono- and diglyceride concentrations on particle size and melting rates of ice cream.

    Science.gov (United States)

    Cropper, S L; Kocaoglu-Vurma, N A; Tharp, B W; Harper, W J

    2013-06-01

    The objective of this study was to determine how varying concentrations of the stabilizer, locust bean gum (LBG), and different levels of the emulsifier, mono- and diglycerides (MDGs), influenced fat aggregation and melting characteristics of ice cream. Ice creams were made containing MDGs and LBG singly and in combination at concentrations ranging between 0.0% to 0.14% and 0.0% to 0.23%, respectively. Particle size analysis, conducted on both the mixes and ice cream, and melting rate testing on the ice cream were used to determine fat aggregation. No significant differences (P ice cream mixes. However, higher concentrations of both LBG and MDG in the ice creams resulted in values that were larger than the control. This study also found an increase in the particle size values when MDG levels were held constant and LBG amounts were increased in the ice cream. Ice creams with higher concentrations of MDG and LBG together had the greatest difference in the rate of melting than the control. The melting rate decreased with increasing LBG concentrations at constant MDG levels. These results illustrated that fat aggregation may not only be affected by emulsifiers, but that stabilizers may play a role in contributing to the destabilization of fat globules.

  5. Inline Measurement of Particle Concentrations in Multicomponent Suspensions using Ultrasonic Sensor and Least Squares Support Vector Machines.

    Science.gov (United States)

    Zhan, Xiaobin; Jiang, Shulan; Yang, Yili; Liang, Jian; Shi, Tielin; Li, Xiwen

    2015-09-18

    This paper proposes an ultrasonic measurement system based on least squares support vector machines (LS-SVM) for inline measurement of particle concentrations in multicomponent suspensions. Firstly, the ultrasonic signals are analyzed and processed, and the optimal feature subset that contributes to the best model performance is selected based on the importance of features. Secondly, the LS-SVM model is tuned, trained and tested with different feature subsets to obtain the optimal model. In addition, a comparison is made between the partial least square (PLS) model and the LS-SVM model. Finally, the optimal LS-SVM model with the optimal feature subset is applied to inline measurement of particle concentrations in the mixing process. The results show that the proposed method is reliable and accurate for inline measuring the particle concentrations in multicomponent suspensions and the measurement accuracy is sufficiently high for industrial application. Furthermore, the proposed method is applicable to the modeling of the nonlinear system dynamically and provides a feasible way to monitor industrial processes.

  6. Influence of the Polyvinyl Pyrrolidone Concentration on Particle Size and Dispersion of ZnS Nanoparticles Synthesized by Microwave Irradiation

    Directory of Open Access Journals (Sweden)

    Nayereh Soltani

    2012-09-01

    Full Text Available Zinc sulfide semiconductor nanoparticles were synthesized in an aqueous solution of polyvinyl pyrrolidone via a simple microwave irradiation method. The effect of the polymer concentration and the type of sulfur source on the particle size and dispersion of the final ZnS nanoparticle product was carefully examined. Microwave heating generally occurs by two main mechanisms: dipolar polarization of water and ionic conduction of precursors. The introduction of the polymer affects the heating rate by restriction of the rotational motion of dipole molecules and immobilization of ions. Consequently, our results show that the presence of the polymer strongly affects the nucleation and growth rates of the ZnS nanoparticles and therefore determines the average particle size and the dispersion. Moreover, we found that PVP adsorbed on the surface of the ZnS nanoparticles by interaction of the C–N and C=O with the nanoparticle’s surface, thereby affording protection from agglomeration by steric hindrance. Generally, with increasing PVP concentration, mono-dispersed colloidal solutions were obtained and at the optimal PVP concentration (5%, sufficiently small size and narrow size distributions were obtained from both sodium sulfide and thioacetamide sulfur sources. Finally, the sulfur source directly influences the reaction mechanism and the final particle morphology, as well as the average size.

  7. Numerical simulation on the opto-electro-kinetic patterning for rapid concentration of particles in a microchannel.

    Science.gov (United States)

    Kim, Dong; Shim, Jaesool; Chuang, Han-Sheng; Kim, Kyung Chun

    2015-05-01

    This paper presents a mathematical model for laser-induced rapid electro-kinetic patterning (REP) to elucidate the mechanism for concentrating particles in a microchannel non-destructively and non-invasively. COMSOL(®)(v4.2a) multiphysics software was used to examine the effect of a variety of parameters on the focusing performance of the REP. A mathematical model of the REP was developed based on the AC electrothermal flow (ACET) equations, the dielectrophoresis (DEP) equation, the energy balance equation, the Navier-Stokes equation, and the concentration-distribution equation. The medium was assumed to be a diluted solute, and different electric potentials and laser illumination were applied to the desired place. Gold (Au) electrodes were used at the top and bottom of a microchannel. For model validation, the simulation results were compared with the experimental data. The results revealed the formation of a toroidal microvortex via the ACET effect, which was generated due to laser illumination and joule-heating in the area of interest. In addition, under some conditions, such as the frequency of AC, the DEP velocity, and the particle size, the ACET force enhances and compresses resulting in the concentration of particles. The conditions of the DEP velocity and the ACET velocity are presented in detail with a comparison of the experimental results.

  8. Light concentration in the near-field of dielectric spheroidal particles with mesoscopic sizes

    Science.gov (United States)

    Mendes, Manuel J.; Tobías, Ignacio; Martí, Antonio; Luque, Antonio

    2011-08-01

    This paper presents a numerical study of the light focusing properties of dielectric spheroids with sizes comparable to the illuminating wavelength. An analytical separation-of-variables method is used to determine the electric field distribution inside and in the near-field outside the particles. An optimization algorithm was implemented in the method to determine the particles' physical parameters that maximize the forward scattered light in the near-field region. It is found that such scatterers can exhibit pronounced electric intensity enhancement (above 100 times the incident intensity) in their close vicinity, or along wide focal regions extending to 10 times the wavelength. The results reveal the potential of wavelength-sized spheroids to manipulate light beyond the limitations of macroscopic geometrical optics. This can be of interest for several applications, such as light management in photovoltaics.

  9. Monitoring sand particle concentration in multiphase flow using acoustic emission technology

    OpenAIRE

    El-Alej, Mohamed Essid

    2014-01-01

    Multiphase flow is the simultaneous flow of two or several phases through a system such as a pipe. This common phenomenon can be found in the petroleum and chemical engineering industrial fields. Transport of sand particles in multiphase production has attracted considerable attention given sand production is a common problem especially to the oil and gas industry. The sand production causes loss of pipe wall thickness which can lead to expensive failures and loss of product...

  10. Analysis of the Reduction Rate of Hematite Concentrate Particles in the Solid State by H2 or CO in a Drop-Tube Reactor Through CFD Modeling

    Science.gov (United States)

    Fan, De-Qiu; Sohn, H. Y.; Elzohiery, Mohamed

    2017-10-01

    The kinetic analysis of the reduction of hematite concentrate particles by individual reducing gas H2 or CO was performed using a computational fluid dynamics (CFD)-based approach in this paper. The particle residence time was calculated through the integration of the equation of particle motion. Non-uniform particle temperature profiles inside the reactor were obtained, and were taken into consideration for the kinetic analysis. The calculated reduction degrees based on this approach are in good agreement with the experimental values.

  11. Biological Effects of Osteoblast-Like Cells on Nanohydroxyapatite Particles at a Low Concentration Range

    OpenAIRE

    Xiaochen Liu; Jie Wei; Shicheng Wei

    2011-01-01

    The biological effects of osteoblast-like MG-63 cells on nanohydroxyapatite (n-HA) at the low concentration range (5–25  g/mL) for 5 days was investigated. The results showed the viability and actin cytoskeleton of the cells descended with the increase of the concentration of n-HA, and the actin cytoskeleton of cells was depolymerised and became more disordered. Apoptotic rate of cells (1.85%, 1.99%, and 2.29%) increased with the increase of n-HA concentration (5, 15, and 25  g/mL) and be...

  12. A pilot study to assess ground-level ambient air concentrations of fine particles and carbon monoxide in urban Guatemala.

    Science.gov (United States)

    Shendell, Derek G; Naeher, Luke P

    2002-11-01

    Ambient concentrations and the elemental composition of particles less than 2.5 microm in diameter (PM2.5), as well as carbon monoxide (CO) concentrations, were measured at ground-level in three Guatemalan cities in summer 1997: Guatemala City, Quetzaltenango, and Antigua. This pilot study also included quantitative and qualitative characterizations of microenvironment conditions, e.g., local meteorology, reported elsewhere. The nondestructive X-ray fluorescence elemental analysis (XRF) of Teflon filters was conducted. The highest integrated average PM2.5. concentrations in an area (zona) of Guatemala City and Quetzaltenango were 150 microg m(-3) (zona 12) and 120 microg m(-3) (zona 2), respectively. The reported integrated average PM2.5 concentration for Antigua was 5 microg m(-3). The highest observed half-hour and monitoring period average CO concentrations in Guatemala City were 10.9 ppm (zona 8) and 7.2 ppm (zonas 8 and 10), respectively. The average monitoring period CO concentration in Antigua was 2.6 ppm. Lead and bromine concentrations were negligible, indicative of the transition to unleaded fuel use in cars and motorcycles. The XRF results suggested sources of air pollution in Guatemala, where relative rankings varied by city and by zonas within each city, were fossil fuel combustion emitting hydrocarbons, combustion of sulfurous conventional fuels, soil/roadway dust, farm/agricultural dust, and vehicles (evaportion of gas, parts' wear).

  13. Biological Effects of Osteoblast-Like Cells on Nanohydroxyapatite Particles at a Low Concentration Range

    Directory of Open Access Journals (Sweden)

    Xiaochen Liu

    2011-01-01

    Full Text Available The biological effects of osteoblast-like MG-63 cells on nanohydroxyapatite (n-HA at the low concentration range (5–25 g/mL for 5 days was investigated. The results showed the viability and actin cytoskeleton of the cells descended with the increase of the concentration of n-HA, and the actin cytoskeleton of cells was depolymerised and became more disordered. Apoptotic rate of cells (1.85%, 1.99%, and 2.29% increased with the increase of n-HA concentration (5, 15, and 25 g/mL and become significantly higher than the control. Total intracellular protein content decreased with n-HA concentration increase, showing significant difference between 25 g/mL and the control, and no significant change of ALP activity was observed at the 5th day. The results revealed that the cell growth was inhibited by n-HA in a concentration-dependent manner, and the obvious biological effects of MG-63 cells on n-HA existed at the low concentration range from 5 to 25 g/mL.

  14. Rolling forecasting model of PM2.5 concentration based on support vector machine and particle swarm optimization

    Science.gov (United States)

    Zhang, Chang-Jiang; Dai, Li-Jie; Ma, Lei-Ming

    2016-10-01

    The data of current PM2.5 model forecasting greatly deviate from the measured concentration. In order to solve this problem, Support Vector Machine (SVM) and Particle Swarm Optimization (PSO) are combined to build a rolling forecasting model. The important parameters (C and γ) of SVM are optimized by PSO. The data (from February to July in 2015), consisting of measured PM2.5 concentration, PM2.5 model forecasting concentration and five main model forecasting meteorological factors, are provided by Shanghai Meteorological Bureau in Pudong New Area. The rolling model is used to forecast hourly PM2.5 concentration in 12 hours in advance and the nighttime average concentration (mean value from 9 pm to next day 8 am) during the upcoming day. The training data and the optimal parameters of SVM model are different in every forecasting, that is to say, different models (dynamic models) are built in every forecasting. SVM model is compared with Radical Basis Function Neural Network (RBFNN), Multi-variable Linear Regression (MLR) and WRF-CHEM. Experimental results show that the proposed model improves the forecasting accuracy of hourly PM2.5 concentration in 12 hours in advance and nighttime average concentration during the upcoming day. SVM model performs better than MLR, RBFNN and WRF-CHEM. SVM model greatly improves the forecasting accuracy of PM2.5 concentration one hour in advance, according with the result concluded from previous research. The rolling forecasting model can be applied to the field of PM2.5 concentration forecasting, and can offer help to meteorological administration in PM2.5 concentration monitoring and forecasting.

  15. Dietary forage concentration and particle size affect sorting, feeding behaviour, intake and growth of Chinese Holstein male calves.

    Science.gov (United States)

    Muhammad, A U R; Xia, C Q; Cao, B H

    2016-04-01

    The objective of study was to evaluate the effect of forage concentration (F:C) and forage particle length (FPL) on sorting, feeding behaviour, intake, growth and body measurements of growing calves. Twenty-eight weaned calves of body weight 156.79 ± 33.44 (mean ± SD) were used in 2 × 2 factorial arrangements with the factors FPL of hay grass (full and short) and hay grass concentrations (low, 50% and high, 65%). The treatments were as follows: full length (FL) with low F:C (50:50), FL with high F:C(65:35), short length (SL) with low F:C (50:50) and SL with high F:C (65:35). Increasing F:C and decreasing FPL enhanced sorting for short and fine particle and sorting against long particle (p behaviour, interaction for eating time and eating time per kilogram DM was present. Increasing the F:C increased the eating time in both FL and SL (p behaviour (p behaviour.

  16. Atmospheric trace element concentrations in total suspended particles near Paris, France

    Science.gov (United States)

    Ayrault, Sophie; Senhou, Abderrahmane; Moskura, Mélanie; Gaudry, André

    2010-09-01

    To evaluate today's trace element atmospheric concentrations in large urban areas, an atmospheric survey was carried out for 18 months, from March 2002 to September 2003, in Saclay, nearby Paris. The total suspended particulate matter (TSP) was collected continuously on quartz fibre filters. The TSP contents were determined for 36 elements (including Ag, Bi, Mo and Sb) using two analytical methods: Instrumental Neutron Activation Analysis (INAA) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The measured concentrations were in agreement within the uncertainties with the certified values for the polycarbonate reference material filter SRM-2783 (National Institute for Standard Technology NIST, USA). The measured concentrations were significantly lower than the recommended atmospheric concentrations. In 2003, the Pb atmospheric level at Saclay was 15 ng/m 3, compared to the 500 ng/m 3 guideline level and to the 200 ng/m 3 observed value in 1994. The typical urban background TSP values of 1-2, 0.2-1, 4-6, 10-30 and 3-5 ng/m 3 for As, Co, Cr, Cu and Sb, respectively, were inferred from this study and were compared with the literature data. The typical urban background TSP concentrations could not be realised for Cd, Pb and Zn, since these air concentrations are highly influenced by local features. The Zn concentrations and Zn/Pb ratio observed in Saclay represented a characteristic fingerprint of the exceptionally large extent of zinc-made roofs in Paris and its suburbs. The traffic-related origin of Ba, Cr, Cu, Pb and Sb was demonstrated, while the atmospheric source(s) of Ag was not identified.

  17. Estimate of main local sources to ambient ultrafine particle number concentrations in an urban area

    Science.gov (United States)

    Rahman, Md Mahmudur; Mazaheri, Mandana; Clifford, Sam; Morawska, Lidia

    2017-09-01

    Quantifying and apportioning the contribution of a range of sources to ultrafine particles (UFPs, D statistical modelling and other exploratory tools. The Bayesian model was trained on the PNC data on days where NP formations were known to have not occurred, hourly traffic counts, solar radiation data, and smooth daily trend. The model was applied to apportion and quantify the contribution of NP formations and local traffic and non-traffic sources to UFPs. The data analysis incorporated long-term measured time-series of total PNC (D ≥ 6 nm), particle number size distributions (PSD, D = 8 to 400 nm), PM2.5, PM10, NOx, CO, meteorological parameters and traffic counts at a stationary monitoring site. The developed Bayesian model showed reliable predictive performances in quantifying the contribution of NP formation events to UFPs (up to 4 × 104 particles cm- 3), with a significant day to day variability. The model identified potential NP formation and no-formations days based on PNC data and quantified the sources contribution to UFPs. Exploratory statistical analyses show that total mean PNC during the middle of the day was up to 32% higher than during peak morning and evening traffic periods, which were associated with NP formation events. The majority of UFPs measured during the peak traffic and NP formation periods were between 30-100 nm and smaller than 30 nm, respectively. To date, this is the first application of Bayesian model to apportion different sources contribution to UFPs, and therefore the importance of this study is not only in its modelling outcomes but in demonstrating the applicability and advantages of this statistical approach to air pollution studies.

  18. Turbulent Concentration of MM-Size Particles in the Protoplanetary Nebula: Scaled-Dependent Multiplier Functions

    Science.gov (United States)

    Cuzzi, Jeffrey N.; Hartlep, Thomas; Weston, B.; Estremera, Shariff Kareem

    2014-01-01

    The initial accretion of primitive bodies (asteroids and TNOs) from freely-floating nebula particles remains problematic. Here we focus on the asteroids where constituent particle (read "chondrule") sizes are observationally known; similar arguments will hold for TNOs, but the constituent particles in those regions will be smaller, or will be fluffy aggregates, and are unobserved. Traditional growth-bysticking models encounter a formidable "meter-size barrier" [1] (or even a mm-cm-size barrier [2]) in turbulent nebulae, while nonturbulent nebulae form large asteroids too quickly to explain long spreads in formation times, or the dearth of melted asteroids [3]. Even if growth by sticking could somehow breach the meter size barrier, other obstacles are encountered through the 1-10km size range [4]. Another clue regarding planetesimal formation is an apparent 100km diameter peak in the pre-depletion, pre-erosion mass distribution of asteroids [5]; scenarios leading directly from independent nebula particulates to this size, which avoid the problematic m-km size range, could be called "leapfrog" scenarios [6-8]. The leapfrog scenario we have studied in detail involves formation of dense clumps of aerodynamically selected, typically mm-size particles in turbulence, which can under certain conditions shrink inexorably on 100-1000 orbit timescales and form 10-100km diameter sandpile planetesimals. The typical sizes of planetesimals and the rate of their formation [7,8] are determined by a statistical model with properties inferred from large numerical simulations of turbulence [9]. Nebula turbulence can be described by its Reynolds number Re = L/eta sup(4/3), where L = ETA alpha sup (1/2) the largest eddy scale, H is the nebula gas vertical scale height, and a the nebula turbulent viscosity parameter, and ? is the Kolmogorov or smallest scale in turbulence (typically about 1km), with eddy turnover time t?. In the nebula, Re is far larger than any numerical simulation can

  19. Effect of carrier and particle concentration on ultrasound properties of magnetic nanofluids.

    Science.gov (United States)

    Patel, Jay Kumar; Parekh, Kinnari

    2015-01-01

    Ultrasound wave propagation in nanofluids and its rheological behavior has been studied as a function of solid volume fraction, temperature and magnetic field for magnetic nanofluids synthesized in kerosene and transformer oil. Ultrasonic velocity decreases while viscosity increases with increasing volume fraction. The attenuation of ultrasonic wave is explained using dipolar coupling co-efficient which favors oligomer structures with increasing number density of particles. The structure formation increases further with increase in magnetic field which is prominent in transformer oil compared to kerosene. This difference can be due to the structural difference between these two carriers.

  20. The VLDL receptor promotes lipotoxicity and increases mortality in mice following an acute myocardial infarction

    Science.gov (United States)

    Perman, Jeanna C.; Boström, Pontus; Lindbom, Malin; Lidberg, Ulf; StÅhlman, Marcus; Hägg, Daniel; Lindskog, Henrik; Scharin Täng, Margareta; Omerovic, Elmir; Mattsson Hultén, Lillemor; Jeppsson, Anders; Petursson, Petur; Herlitz, Johan; Olivecrona, Gunilla; Strickland, Dudley K.; Ekroos, Kim; Olofsson, Sven-Olof; Borén, Jan

    2011-01-01

    Impaired cardiac function is associated with myocardial triglyceride accumulation, but it is not clear how the lipids accumulate or whether this accumulation is detrimental. Here we show that hypoxia/ischemia-induced accumulation of lipids in HL-1 cardiomyocytes and mouse hearts is dependent on expression of the VLDL receptor (VLDLR). Hypoxia-induced VLDLR expression in HL-1 cells was dependent on HIF-1α through its interaction with a hypoxia-responsive element in the Vldlr promoter, and VLDLR promoted the endocytosis of lipoproteins. Furthermore, VLDLR expression was higher in ischemic compared with nonischemic left ventricles from human hearts and was correlated with the total lipid droplet area in the cardiomyocytes. Importantly, Vldlr–/– mice showed improved survival and decreased infarct area following an induced myocardial infarction. ER stress, which leads to apoptosis, is known to be involved in ischemic heart disease. We found that ischemia-induced ER stress and apoptosis in mouse hearts were reduced in Vldlr–/– mice and in mice treated with antibodies specific for VLDLR. These findings suggest that VLDLR-induced lipid accumulation in the ischemic heart worsens survival by increasing ER stress and apoptosis. PMID:21670500

  1. Estimation of ultrafine particle concentrations at near-highway residences using data from local and central monitors

    Science.gov (United States)

    Fuller, Christina H.; Brugge, Doug; Williams, Paige L.; Mittleman, Murray A.; Durant, John L.; Spengler, John D.

    2012-09-01

    Ultrafine particles (UFP; aerodynamic diameter predict hourly UFP concentration measured at residences in an urban community with a major interstate highway and; (2) determine if meteorology and proximity to traffic improve explanatory power. Short-term (1-3 weeks) residential monitoring of UFP concentration was conducted at 18 homes. Long-term monitoring was conducted at two near-highway monitoring sites and a central site. We created models of outdoor residential UFP concentration based on concentrations at the near-highway site, at the central site, at both sites together and without fixed sites. UFP concentration at residential sites was more highly correlated with those at a near-highway site than a central site. In regression models of each site alone, a 10% increase in UFP concentration at a near-highway site was associated with a 6% (95% CI: 6%, 7%) increase at residences while a 10% increase in UFP concentration at the central site was associated with a 3% (95% CI: 2%, 3%) increase at residences. A model including both sites showed minimal change in the magnitude of the association between the near-highway site and the residences, but the estimated association with UFP concentration at the central site was substantially attenuated. These associations remained after adjustment for other significant predictors of residential UFP concentration, including distance from highway, wind speed, wind direction, highway traffic volume and precipitation. The use of a central site as an estimate of personal exposure for populations near local emissions of traffic-related air pollutants may result in exposure misclassification.

  2. Concentration and vertical flux of Fukushima-derived radiocesium in sinking particles from two sites in the Northwestern Pacific Ocean

    Directory of Open Access Journals (Sweden)

    M. C. Honda

    2013-06-01

    Full Text Available At two stations in the western North Pacific, K2 in the subarctic gyre and S1 in the subtropical gyre, time-series sediment traps were collecting sinking particles when the Fukushima Daiichi Nuclear Power Plant (FNPP1 accident occurred on 11 March 2011. Radiocesium (134Cs and 137Cs derived from the FNPP1 accident was detected in sinking particles collected at 500 m in late March 2011 and at 4810 m in early April 2011 at both stations. The sinking velocity of 134Cs and 137Cs was estimated to be 22 to 71 m day−1 between the surface and 500 m and >180 m day−1 between 500 m and 4810 m. 137Cs concentrations varied from 0.14 to 0.25 Bq g−1 dry weight. These values are higher than those of surface seawater, suspended particles, and zooplankton collected in April 2011. Although the radiocesium may have been adsorbed onto or incorporated into clay minerals, correlations between 134Cs and lithogenic material were not always significant; therefore, the form of the cesium associated with the sinking particles is still an open question. The total 137Cs inventory by late June at K2 and by late July at S1 was 0.5 to 1.7 Bq m−2 at both depths. Compared with 137Cs input from both stations by April 2011, estimated from the surface 137Cs concentration and mixed-layer depth and by assuming that the observed 137Cs flux was constant throughout the year, the estimated removal rate of 137Cs from the upper layer (residence time in the upper layer was 0.3 to 1.5% yr−1 (68 to 312 yr. The estimated removal rates and residence times are comparable to previously reported values after the Chernobyl accident (removal rate: 0.2–1%, residence time: 130–390 yr.

  3. Concentrated, polydisperse solutions of colloidal particles. Light scattering and sedimentation of hard-sphere mixture

    NARCIS (Netherlands)

    Vrij, A.

    1982-01-01

    The usefulness of the hard-sphere model in characterizing polydispersity in concentrated colloidal solutions is stressed. A recently derived equation for (∂ρi/∂μj)μ is used to give a simpler route for application to light scattering and sedimentation in multicomponent and polydisperse systems. Some

  4. Brominated flame retardants in the urban atmosphere of Northeast China: Concentrations, temperature dependence and gas-particle partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Hong; Li, Wen-Long; Liu, Li-Yan; Song, Wei-Wei; Ma, Wan-Li, E-mail: mawanli002@163.com; Li, Yi-Fan, E-mail: ijrc_pts_paper@yahoo.com

    2014-09-01

    57 pairs of air samples (gas and particle phases) were collected using a high volume air sampler in a typical city of Northeast China. Brominated flame retardants (BFRs) including 13 polybrominated diphenyl ethers (PBDEs, including BDEs 17, 28, 47, 49, 66, 85, 99, 100, 138, 153, 154, 183, and 209) and 9 alternative BFRs (p-TBX, PBBZ, PBT, PBEB, DPTE, HBBZ, γ-HBCD, BTBPE, and DBDPE) were analyzed. The annual average total concentrations of the 13 PBDEs and the 9 alternative BFRs were 69 pg/m{sup 3} and 180 pg/m{sup 3}, respectively. BDE 209 and γ-HBCD were the dominant congeners, according to the one-year study. The partial pressure of BFRs in the gas phase was significantly correlated with the ambient temperature, except for BDE 85, γ-HBCD and DBDPE, indicating the important influence of ambient temperature on the behavior of BFRs in the atmosphere. It was found that the gas–particle partitioning coefficients (logK{sub p}) for most low molecular weight BFRs were highly temperature dependent as well. Gas–particle partitioning coefficients (logK{sub p}) also correlated with the sub-cooled liquid vapor pressure (logP{sub L}{sup o}). Our results indicated that absorption into organic matter is the main control mechanism for the gas–particle partitioning of atmospheric PBDEs. - Highlights: • Both PBDEs and alternative BFRs were analyzed in the atmosphere of Northeast China. • Partial pressure of BFRs was significantly correlated with the ambient temperature. • A strong temperature dependence of gas-particle partitioning was found. • Absorption into organic matter was the control mechanism for G-P partitioning.

  5. Trace element concentrations on fine particles in the Ohio River Valley

    Energy Technology Data Exchange (ETDEWEB)

    Tuncel, S.G.; Gordon, G.E.; Olmez, I.; Parrington, J.R.; Shaw, R.W. Jr.; Paur, R.J.

    1986-04-01

    Trace element compositions of airborne particles are important for determining sources and behavior of regional aerosol, as emissions from major sources are characterized by their elemental composition patterns. The authors investigated airborne trace elements in a complex regional environment through application of receptor models. A subset (200) of fine fraction samples in the Ohio River Valley (ORV) and analyzed by X-ray fluorescence (XRF) were reanalyzed by instrumental neutron activation analysis (INAA). The combined data set, XRF plus INAA, was subjected to receptor-model interpretations, including chemical mass balances (CMBs) and factor analysis (FA). Back trajectories of air masses were calculated for each sampling period and used with XRF data to select samples to be analyzed by INAA.

  6. Aircraft observations and model simulations of concentration and particle size distribution in the Eyjafjallajökull volcanic ash cloud

    OpenAIRE

    Dacre, H. F.; A. L. M. Grant; Johnson, B. T.

    2013-01-01

    The Eyjafjallajökull volcano in Iceland emitted a cloud of ash into the atmosphere during April and May 2010. Over the UK the ash cloud was observed by the FAAM BAe-146 Atmospheric Research Aircraft which was equipped with in-situ probes measuring the concentration of volcanic ash carried by particles of varying sizes. The UK Met Office Numerical Atmospheric-dispersion Modelling Environment (NAME) has been used to simulate the evolution of the ash cloud emitted by the Eyjafjallajökull volcano...

  7. Aircraft observations and model simulations of concentration and particle size distribution in the Eyjafjallajökull volcanic ash cloud

    OpenAIRE

    Dacre, H. F.; A. L. M. Grant; Johnson, B. T.

    2012-01-01

    The Eyjafjallajökull volcano in Iceland emitted a cloud of ash into the atmosphere during April and May 2010. Over the UK the ash cloud was observed by the FAAM BAe-146 Atmospheric Research Aircraft which was equipped with in-situ probes measuring the concentration of volcanic ash carried by particles of varying sizes. The UK Met Office Numerical Atmospheric-dispersion Modelling Environment (NAME) has been used to simulate the evolution of the ash cloud emitted by the Eyjafjallajökull volcano...

  8. Real-time texture analysis for identifying optimum microbubble concentration in 2-D ultrasonic particle image velocimetry.

    Science.gov (United States)

    Niu, Lili; Qian, Ming; Yan, Liang; Yu, Wentao; Jiang, Bo; Jin, Qiaofeng; Wang, Yanping; Shandas, Robin; Liu, Xin; Zheng, Hairong

    2011-08-01

    Many recent studies on ultrasonic particle image velocimetry (Echo PIV) showed that the accuracy of two-dimensional (2-D) flow velocity measured depends largely on the concentration of ultrasound contrast agents (UCAs) during imaging. This article presents a texture-based method for identifying the optimum microbubble concentration for Echo PIV measurements in real-time. The texture features, standard deviation of gray level, and contrast, energy and homogeneity of gray level co-occurrence matrix were extracted from ultrasound contrast images of rotational and pulsatile flow (10 MHz) in vitro and in vivo mouse common carotid arterial flow (40 MHz) with UCAs at various concentrations. The results showed that, at concentration of 0.8∼2 × 10³ bubbles/mL in vitro and 1∼5 × 10⁵ bubbles/mL in vivo, image texture features had a peak value or trough value, and velocity vectors with high accuracy can be obtained. Otherwise, poor quality velocity vectors were obtained. When the texture features were used as a feature set, the accuracy of K-nearest neighbor classifier can reach 86.4% in vitro and 87.5% in vivo, respectively. The texture-based method is shown to be able to quickly identify the optimum microbubble concentration and improve the accuracy for Echo PIV imaging.

  9. Investigating near-road particle number concentrations along a busy urban corridor with varying built environment characteristics

    Science.gov (United States)

    Xu, Junshi; Wang, An; Hatzopoulou, Marianne

    2016-10-01

    This study aimed at capturing the determinants of near-road concentrations of ultrafine particles (UFP) using linear mixed-effects models, investigating the effects of meteorology, built environment, and traffic. In addition, the differences in the levels of UFP between both sides of the road were investigated. To reach these objectives, field measurements were conducted on 16 weekdays in the months of March and April 2015, along Papineau Avenue, a high-volume street in Montreal, Canada. Four sites were identified varying in land use, building height, and road characteristics. Air quality measurements were conducted at each location (on both sides of the road) for two consecutive hours, at four different times during the day and repeated four times, leading to a total of 16 visits per location. Traffic volume and composition was also recorded. On-site meteorological variables including wind speed, wind direction, temperature and relative humidity were collected using a portable weather station. Linear mixed-effects models with random intercept were developed for both dependent variables: the natural logarithm of the mean UFP concentration and the difference in UFP concentrations between two sides of the road. Lower temperatures and wind speeds were associated with increased UFP concentrations. Winds orthogonal to the road tended to increase UFP concentrations as well as the differences between both sides of the road. Finally, built environment variables such as the presence of open areas and buildings on both sides of the road, had a positive influence on the difference between UFP on the two sides.

  10. Particle Concentrations Inside a Tavern Before and After Prohibition of Smoking: Evaluating the Performance of an Indoor Air Quality Model.

    Science.gov (United States)

    Ott, Wayne; Switzer, Paul; Robinson, John

    1996-12-01

    Measurements were made of respirable suspended particles (RSP) in a large sports tavern on 26 dates over approximately two years in which smoking was allowed, followed by measurements on 50 dates during the year after smoking was prohibited. The smoking prohibition occurred without warning when the city government passed a regulation restricting smoking in local restaurants and taverns. Two follow-up field surveys, consisting of 24 and 26 visits, respectively, were conducted to measure changes in RSP levels after smoking was prohibited. No decrease in tavern attendance was evident after smoking was prohibited. During the smoking period, the average RSP concentration was 56.8 |ig/m3 above the outdoor concentrations, but the average abruptly dropped to 5.9 ug/m3 above outdoor levels-a 90% decrease- on 24 visits in the first two months immediately after smoking was prohibited (first follow-up study). A second set of 26 follow-up visits (matched by time of day, day of the week, and season to the earlier smoking visits) yielded an average concentration of 12.9 jig/m3 above the outdoor levels, or an overall decrease in the average RSP concentration of 77% compared with the smoking period. During the smoking period, RSP concentrations more than 100 ug/m3 above outdoor levels occurred on 30.7% of the visits. During the 50 nonsmoking visits, 92% of the RSP concentrations were less than 20 u,g/m3 above outdoor levels, and no concentration exceeded 100 ug/m3 on any nonsmoking visit. The data show there was a striking decline in indoor RSP concentrations in the tavern after smoking was prohibited. The indoor concentration observed in the nonsmoking periods (9.1 u.g/m3 average for all nonsmoking visits) was attributed to cooking and resuspended dust. A mathematical model based on the mass balance equation was developed that included smoking, cooking, and resuspended dust. Using cigarette emission rates from the literature, the tavern volume of 521 m3, and the air exchange rate

  11. Serum paraoxonase-1 activity is more closely related to HDL particle concentration and large HDL particles than to HDL cholesterol in Type 2 diabetic and non-diabetic subjects.

    Science.gov (United States)

    Dullaart, Robin P F; Otvos, James D; James, Richard W

    2014-08-01

    We determined relationships of the anti-oxidative enzyme, paraoxonase-1 (PON-1), with high density lipoprotein (HDL) subfractions, and tested whether these relationships are stronger than those with HDL cholesterol and apolipoprotein A-I (apoA-I) in subjects with and without type 2 diabetes mellitus (T2DM). Serum PON-1 (arylesterase activity) and HDL subfractions (nuclear magnetic resonance spectroscopy) were determined in 67 T2DM patients and in 56 non-diabetic subjects. PON-1 activity, HDL cholesterol and apoA-I were decreased in T2DM (all pHDL particle concentration was unaltered, but large HDL particles, medium HDL particles and HDL particle size were decreased, whereas small HDL particles were increased in T2DM (all pHDL cholesterol than to apoA-I (p=0.001). In turn, the positive relationship of PON-1 with the HDL particle concentration and with large HDL particles was stronger than that with HDL cholesterol (both pHDL cholesterol or HDL particle characteristics. PON-1 activity is more closely related to the HDL particle concentration or large HDL particles than to HDL cholesterol. Impaired PON-1 activity in T2DM is not to a considerable extent explained by altered HDL subfraction levels. Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  12. The effect of a concentration-dependent viscosity on particle transport in a channel flow with porous walls

    KAUST Repository

    Herterich, James G.

    2014-02-02

    The transport of a dilute suspension of particles through a channel with porous walls, accounting for the concentration dependence of the viscosity, is analyzed. In particular, we study two cases of fluid permeation through the porous channel walls: (1) at a constant flux and (2) dependent on the pressure drop across the wall. We also consider the effect of mixing the suspension first compared with point injection by considering inlet concentration distributions of different widths. We find that a pessimal inlet distribution width exists that maximizes the required hydrodynamic pressure for a constant fluid influx. The effect of an external hydrodynamic pressure, to compensate for the reduced transmembrane pressure difference due to osmotic pressure, is investigated. © 2014 American Institute of Chemical Engineers.

  13. Forty-three loci associated with plasma lipoprotein size, concentration, and cholesterol content in genome-wide analysis.

    Directory of Open Access Journals (Sweden)

    Daniel I Chasman

    2009-11-01

    Full Text Available While conventional LDL-C, HDL-C, and triglyceride measurements reflect aggregate properties of plasma lipoprotein fractions, NMR-based measurements more accurately reflect lipoprotein particle concentrations according to class (LDL, HDL, and VLDL and particle size (small, medium, and large. The concentrations of these lipoprotein sub-fractions may be related to risk of cardiovascular disease and related metabolic disorders. We performed a genome-wide association study of 17 lipoprotein measures determined by NMR together with LDL-C, HDL-C, triglycerides, ApoA1, and ApoB in 17,296 women from the Women's Genome Health Study (WGHS. Among 36 loci with genome-wide significance (P<5x10(-8 in primary and secondary analysis, ten (PCCB/STAG1 (3q22.3, GMPR/MYLIP (6p22.3, BTNL2 (6p21.32, KLF14 (7q32.2, 8p23.1, JMJD1C (10q21.3, SBF2 (11p15.4, 12q23.2, CCDC92/DNAH10/ZNF664 (12q24.31.B, and WIPI1 (17q24.2 have not been reported in prior genome-wide association studies for plasma lipid concentration. Associations with mean lipoprotein particle size but not cholesterol content were found for LDL at four loci (7q11.23, LPL (8p21.3, 12q24.31.B, and LIPG (18q21.1 and for HDL at one locus (GCKR (2p23.3. In addition, genetic determinants of total IDL and total VLDL concentration were found at many loci, most strongly at LIPC (15q22.1 and APOC-APOE complex (19q13.32, respectively. Associations at seven more loci previously known for effects on conventional plasma lipid measures reveal additional genetic influences on lipoprotein profiles and bring the total number of loci to 43. Thus, genome-wide associations identified novel loci involved with lipoprotein metabolism-including loci that affect the NMR-based measures of concentration or size of LDL, HDL, and VLDL particles-all characteristics of lipoprotein profiles that may impact disease risk but are not available by conventional assay.

  14. Ion size effects on the electric double layer of a spherical particle in a realistic salt-free concentrated suspension.

    Science.gov (United States)

    Roa, Rafael; Carrique, Félix; Ruiz-Reina, Emilio

    2011-05-28

    A new modified Poisson-Boltzmann equation accounting for the finite size of the ions valid for realistic salt-free concentrated suspensions has been derived, extending the formalism developed for pure salt-free suspensions [Roa et al., Phys. Chem. Chem. Phys., 2011, 13, 3960-3968] to real experimental conditions. These realistic suspensions include water dissociation ions and those generated by atmospheric carbon dioxide contamination, in addition to the added counterions released by the particles to the solution. The electric potential at the particle surface will be calculated for different ion sizes and compared with classical Poisson-Boltzmann predictions for point-like ions, as a function of particle charge and volume fraction. The realistic predictions turn out to be essential to achieve a closer picture of real salt-free suspensions, and even more important when ionic size effects are incorporated to the electric double layer description. We think that both corrections have to be taken into account when developing new realistic electrokinetic models, and surely will help in the comparison with experiments for low-salt or realistic salt-free systems. This journal is © the Owner Societies 2011

  15. Surface Modification Approach to TiO2 Nanofluids with High Particle Concentration, Low Viscosity, and Electrochemical Activity.

    Science.gov (United States)

    Sen, Sujat; Govindarajan, Vijay; Pelliccione, Christopher J; Wang, Jie; Miller, Dean J; Timofeeva, Elena V

    2015-09-23

    This study presents a new approach to the formulation of functional nanofluids with high solid loading and low viscosity while retaining the surface activity of nanoparticles, in particular, their electrochemical response. The proposed methodology can be applied to a variety of functional nanomaterials and enables exploration of nanofluids as a medium for industrial applications beyond heat transfer fluids, taking advantage of both liquid behavior and functionality of dispersed nanoparticles. The highest particle concentration achievable with pristine 25 nm titania (TiO2) nanoparticles in aqueous electrolytes (pH 11) is 20 wt %, which is limited by particle aggregation and high viscosity. We have developed a scalable one-step surface modification procedure for functionalizing those TiO2 nanoparticles with a monolayer coverage of propyl sulfonate groups, which provides steric and charge-based separation of particles in suspension. Stable nanofluids with TiO2 loadings up to 50 wt % and low viscosity are successfully prepared from surface-modified TiO2 nanoparticles in the same electrolytes. Viscosity and thermal conductivity of the resulting nanofluids are evaluated and compared to nanofluids prepared from pristine nanoparticles. Furthermore, it is demonstrated that the surface-modified titania nanoparticles retain more than 78% of their electrochemical response as compared to that of the pristine material. Potential applications of the proposed nanofluids include, but are not limited to, electrochemical energy storage and catalysis, including photo- and electrocatalysis.

  16. Investigation of a New Electrostatic Sampler for Concentrating Biological and Non-Biological Aerosol Particles

    OpenAIRE

    Roux, Jean-Maxime; Kaspari, Oliver; Heinrich, Renate; Hanschmann, Nicole; Grunow, Roland

    2013-01-01

    The detection of airborne pathogens is becoming a subject of great concern in modern day society. Recent studies have shown that electrostatic samplers are suitable for collecting microorganisms as well as preserving their viability. In most of these studies, flow rates were lower than 12.5 L/min or required a concentration stage to increase the flow rate to 100 L/min. In the present study, a single stage electrostatic sampler was developed for an efficient collection of microorganisms at 100...

  17. Reduction of indoor particles concentration using re-circulating filtration units in Danish dwellings

    DEFF Research Database (Denmark)

    Spilak, Michal; Frederiksen, Marie; Karottki, Gabriela D.;

    2012-01-01

    Exposure to particulate matter has been shown to be associated with an increased risk of cardiovascular and respiratory diseases. The indoor environment contributes significantly to the total exposure to air pollution because of the many hours spent here, quantity of sources and low ventilation....... This exposure can be reduced by using re-circulating filtration units, limiting the impact of outdoor pollution penetration, indoor emissions and decomposition of dust on heated surfaces. The objective of this study was to investigate whether reducing the indoor particulate concentration, by means of specially...

  18. Investigation on particle matter concentration and bacterial bioaerosols in indoor air of prisons

    Directory of Open Access Journals (Sweden)

    Mohammad Sadegh Sekhavatjou

    2014-03-01

    Conclusion: Based on the results, the maximum contamination load and exceeded concentration was observed in public sections and bedchambers. This findings were attributed to the daily entry of new prisoners, high population density in prison, presence of ill prisoners, prisoners with hidden respiratory disease showing no symptoms yet, old building, climatic conditions of the region, low efficiency of ventilation systems, and influx of particulates. To filter and purify prison indoor air, it is crucial to take serious action plans such as reducing criminal population density, sanitary and engineering measures

  19. Adapting a Particle Model for Computing Sulfur Dioxide Concentrations in Mount Rainier Area and Comparing Them to Measured Values

    Science.gov (United States)

    Givati, Reuven

    In this work the SO_2 concentrations measured in the Mt. Rainier area during PREVENT Pacific Northwest Regional Visibility Experiment Using Natural Tracers, June to September 1990), were analyzed with the aid of the MATHEW/ADPIC models (a diagnostic wind model and a particle model) developed by Lawrence Livermore National Laboratory. Some changes were made in the models to adapt them to the specific conditions of this experiment. The models were run on a large domain in western Washington, and the SO_2 concentrations were evaluated at two specific points, Tahoma Woods and Paradise in the Nisqually Valley, the only points near Mt. Rainier where SO_2 concentrations were measured during PREVENT. The changes that were made were: including loss rates of SO_2 by oxidation, using different heights of the top of the boundary layer at different locations, enabling limited area of influence of specific meteorological stations when interpolating the wind fields, and including the possibility of reflection of the air "particles", from the top of the mixed layer. Because of the paucity of the meteorological measurements near the sampling points, an estimation was made about the wind behavior in the valley, based on the phenomena of wind channeling, mountain and valley winds, and historical wind measurements near Mt. Rainier. The models were run for several non-rainy days of PREVENT having large SO_2 concentrations, or that were interesting for other reasons. The agreement between the measured and modeled SO_2 concentrations at Tahoma Woods during the daytime periods, was quite good. Out of 14 days, for which the emissions of the previous night were taken into account, for 12 days (86%) the ratio of the modeled to the measured SO_2 concentrations, at Tahoma Woods during the daytime periods, was in the interval 0.45-2.00. The agreement between the modeled and measured SO_2 concentrations at Tahoma Woods during the nights, and at Paradise, during the day and the night, were not

  20. Atmospheric concentration characteristics and gas-particle partitioning of PCBs in a rural area of eastern Germany

    Energy Technology Data Exchange (ETDEWEB)

    Mandalakis, Manolis [Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, P.O. Box 2208, GR-71003, Heraklion (Greece)]. E-mail: mandalakis@chemistry.uoc.gr; Stephanou, Euripides G. [Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, P.O. Box 2208, GR-71003, Heraklion (Greece)

    2007-05-15

    Atmospheric concentrations of polychlorinated biphenyls (PCBs) were measured in 14 successive daytime and nighttime air samples collected from Melpitz, a rural site in eastern Germany. The average total concentration of PCBs was 110+/-80pgm{sup -3} and they were predominately present in the gas phase ({approx}95%). Composition of individual congeners closely resembled those of Clophen A30 and Aroclor 1232. Partial vapor pressures of PCBs were well correlated with temperature and the steep slopes obtained from Clausius-Clapeyron plots (-4500 to -8000) indicated that evaporation from adjacent land surfaces still controls the atmospheric levels of these pollutants. Particle-gas partitioning coefficients (K{sub P}) of PCBs were well correlated with the respective sub-cooled vapor pressures (P{sub L}{sup o}), but the slopes obtained from logK{sub P} versus logP{sub L}{sup o} plots (-0.16 to -0.59) deviated significantly from the expected value of -1. Overall, gas-particle partitioning of PCBs was better simulated by Junge-Pankow than octanol/air partition coefficient-based model.

  1. Dissipative particle dynamics simulation of flow generated by two rotating concentric cylinders: boundary conditions.

    Science.gov (United States)

    Haber, S; Filipovic, N; Kojic, M; Tsuda, A

    2006-10-01

    The dissipative particle dynamics (DPD) method was used to simulate the flow in a system comprised of a fluid occupying the space between two cylinders rotating with equal angular velocities. The fluid, initially at rest, ultimately reaches a steady, linear velocity distribution (a rigid-body rotation). Since the induced flow field is solely associated with the no-slip boundary condition at the walls, we employed this system as a benchmark to examine the effect of bounce-back reflections, specular reflections, and Pivkin-Karniadakis no-slip boundary conditions, upon the steady-state velocity, density, and temperature distributions. An additional advantage of the foregoing system is that the fluid occupies inherently a finite bounded domain so that the results are affected by the prescribed no-slip boundary conditions only. Past benchmark systems such as Couette flow between two infinite parallel plates or Poiseuille flow in an infinitely long cylinder must employ artificial periodic boundary conditions at arbitrary upstream and downstream locations, a possible source of spurious effects. In addition, the effect of the foregoing boundary conditions on the time evolution of the simulated velocity profile was compared with that of the known, time-dependent analytical solution. It was shown that bounce-back reflection yields the best results for the velocity distributions with small fluctuations in density and temperature at the inner fluid domain and larger deviations near the walls. For the unsteady solutions a good fit is obtained if the DPD friction coefficient is proportional to the kinematic viscosity. Based on dimensional analysis and the numerical results a universal correlation is suggested between the friction coefficient and the kinematic viscosity.

  2. Atmospheric concentration characteristics and gas/particle partitioning of PCBs from the North Pacific to the Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    WANG Zhen; NA Guangshui; GAO Hui; WANG Yanjie; YAO Ziwei

    2014-01-01

    Polychlorinated biphenyls (PCBs) were measured in atmospheric samples collected from the North Pacific to the Arctic Ocean between July and September 2012 to study the atmospheric concentration characteris-tics of PCBs and their gas/particle partitioning. The mean concentration of 26 PCBs (vapor plus particulate phase) (ƩPCBs) was 19.116 pg/m3with a standard deviation of 13.833 pg/m3. Three most abundant conge-ners were CB-28, -52 and -77, accounting for 43.0% toƩPCBs. The predominance of vapor PCBs (79.0% toƩPCBs) in the atmosphere was observed.ƩPCBs were negative correlated with the latitudes and inverse of the absolute temperature (1/T). The significant correlation for most congeners was also observed between the logarithm of gas/particle partition coefficient (logKP) and 1/T. Shallower slopes (from −0.15 to −0.46, average −0.27) were measured from the regression of the logarithm of sub-cooled liquid vapor pressures (logpºL) and logKP for all samples. The difference of the slopes and intercepts among samples was insignifi-cant (p>0.1), implying adsorption and/or absorption processes and the aerosol composition did not differ significantly among different samples. By comparing three models, the J-P adsorption model, the octanol/air partition coefficient (KOA) based model and the soot-air model, the gas/particle partitioning of PCBs in the Arctic atmosphere was simulated more precisely by the soot-air model, and the adsorption onto el-emental carbon is more sensitive than the absorption into organic matters of aerosols, especially for low-chlorinated PCB congeners.

  3. Field evaluation of a new particle concentrator- electrostatic precipitator system for measuring chemical and toxicological properties of particulate matter

    Directory of Open Access Journals (Sweden)

    Pakbin Payam

    2008-11-01

    Full Text Available Abstract Background A newly designed electrostatic precipitator (ESP in tandem with Versatile Aerosol Concentration Enrichment System (VACES was developed by the University of Southern California to collect ambient aerosols on substrates appropriate for chemical and toxicological analysis. The laboratory evaluation of this sampler is described in a previous paper. The main objective of this study was to evaluate the performance of the new VACES-ESP system in the field by comparing the chemical characteristics of the PM collected in the ESP to those of reference samplers operating in parallel. Results The field campaign was carried out in the period from August, 2007 to March, 2008 in a typical urban environment near downtown Los Angeles. Each sampling set was restricted to 2–3 hours to minimize possible sampling artifacts in the ESP. The results showed that particle penetration increases and ozone concentration decreases with increasing sampling flow rate, with highest particle penetration observed between 100 nm and 300 nm. A reference filter sampler was deployed in parallel to the ESP to collect concentration-enriched aerosols, and a MOUDI sampler was used to collect ambient aerosols. Chemical analysis results showed very good agreement between the ESP and MOUDI samplers in the concentrations of trace elements and inorganic ions. The overall organic compound content of PM collected by the ESP, including polycyclic aromatic hydrocarbons (PAHs, hopanes, steranes, and alkanes, was in good agreement with that of the reference sampler, with an average ESP -to -reference concentration ratio of 1.07 (± 0.38. While majority of organic compound ratios were close to 1, some of the semi-volatile organic species had slightly deviated ratios from 1, indicating the possibility of some sampling artifacts in the ESP due to reactions of PM with ozone and radicals generated from corona discharge, although positive and negative sampling artifacts in the

  4. Concentration response functions for ultrafine particles and all-cause mortality and hospital admissions: results of a European expert panel elicitation.

    NARCIS (Netherlands)

    Hoek, G.; Boogaard, H.; Knol, A.B.; de Hartog, J.J.; Slottje, P.; Ayres, J.G.; Borm, P.; Brunekreef, B.; Donaldson, K.; Forastiere, F.; Holgate, S.; Kreyling, W.G.; Nemery, B.; Pekkanen, J.; Stone, V.; Wichmann, H.E.; van der Sluijs, J.P.

    2010-01-01

    Toxicological studies have provided evidence of the toxicity of ultrafine particles (UFP), but epidemiological evidence for health effects of ultrafines is limited. No quantitative summary currently exists of concentration-response functions for ultrafine particles that can be used in health impact

  5. Simultaneous measurement of local particle movement, solids concentrations and bubble properties in fluidized bed reactors using a novel fiber optical technique

    Energy Technology Data Exchange (ETDEWEB)

    Tayebi, Davoud

    1998-12-31

    This thesis develops a new method for simultaneous measurements of local flow properties in highly concentrated multiphase flow systems such as gas-solid fluidized bed reactors. The method is based on fiber optical technique and tracer particles. A particle present in the measuring volume in front of the probe is marked with a fluorescent dye. A light source illuminates the particles and the detecting fibres receive reflected light from uncoated particles and fluorescent light from the tracer particle. Using optical filters, the fluorescent light can be distinguished and together with a small fraction of background light from uncoated particles can be used for determination of local flow properties. Using this method, one can simultaneously measure the local movement of a single tracer particle, local bubble properties and the local solids volume fractions in different positions in the bed. The method is independent of the physical properties of the tracer particles. It is also independent of the local solids concentrations in the range of 0 to 60 vol.-%, but is mainly designed for highly concentrated flow systems. A computer programme that uses good signals from at least three sensors simultaneously to calculate the tracer particle velocity in two dimensions have been developed. It also calculates the bubble properties and local solids volume fractions from the same time series. 251 refs., 150 figs., 5 tabs.

  6. Intraurban Variation of Fine Particle Elemental Concentrations in New York City.

    Science.gov (United States)

    Ito, Kazuhiko; Johnson, Sarah; Kheirbek, Iyad; Clougherty, Jane; Pezeshki, Grant; Ross, Zev; Eisl, Holger; Matte, Thomas D

    2016-07-19

    Few past studies have collected and analyzed within-city variation of fine particulate matter (PM2.5) elements. We developed land-use regression (LUR) models to characterize spatial variation of 15 PM2.5 elements collected at 150 street-level locations in New York City during December 2008-November 2009: aluminum, bromine, calcium, copper, iron, potassium, manganese, sodium, nickel, lead, sulfur, silicon, titanium, vanadium, and zinc. Summer- and winter-only data available at 99 locations in the subsequent 3 years, up to November 2012, were analyzed to examine variation of LUR results across years. Spatial variation of each element was modeled in LUR including six major emission indicators: boilers burning residual oil; traffic density; industrial structures; construction/demolition (these four indicators in buffers of 50 to 1000 m), commercial cooking based on a dispersion model; and ship traffic based on inverse distance to navigation path weighted by associated port berth volume. All the elements except sodium were associated with at least one source, with R(2) ranging from 0.2 to 0.8. Strong source-element associations, persistent across years, were found for residual oil burning (nickel, zinc), near-road traffic (copper, iron, and titanium), and ship traffic (vanadium). These emission source indicators were also significant and consistent predictors of PM2.5 concentrations across years.

  7. A comparison of particle-tracking and solute transport methods for simulation of tritium concentrations and groundwater transit times in river water

    OpenAIRE

    Gusyev, M. A.; D. Abrams; Toews, M. W.; U. Morgenstern; M. K. Stewart

    2014-01-01

    The purpose of this study is to simulate tritium concentrations and groundwater transit times in river water with particle-tracking (MODPATH) and compare them to solute transport (MT3DMS) simulations. Tritium measurements in river water are valuable for the calibration of particle-tracking and solute transport models as well as for understanding of watershed storage dynamics. In a previous study, we simulated tritium concentrations in river water of the western Lake Taupo...

  8. Acute central neuropeptide Y administration increases food intake but does not affect hepatic very low-density lipoprotein (VLDL production in mice.

    Directory of Open Access Journals (Sweden)

    Janine J Geerling

    Full Text Available OBJECTIVE: Central neuropeptide Y (NPY administration stimulates food intake in rodents. In addition, acute modulation of central NPY signaling increases hepatic production of very low-density lipoprotein (VLDL-triglyceride (TG in rats. As hypertriglyceridemia is an important risk factor for atherosclerosis, for which well-established mouse models are available, we set out to validate the effect of NPY on hepatic VLDL-TG production in mice, to ultimately investigate whether NPY, by increasing VLDL production, contributes to the development of atherosclerosis. RESEARCH DESIGN AND METHODS: Male C57Bl/6J mice received an intracerebroventricular (i.c.v. cannula into the lateral (LV or third (3V ventricle of the brain. One week later, after a 4 h fast, the animals received an intravenous (i.v. injection of Tran(35S (100 µCi followed by tyloxapol (500 mg/kg body weight; BW, enabling the study of hepatic VLDL-apoB and VLDL-TG production, respectively. Immediately after the i.v. injection of tyloxapol, the animals received either an i.c.v. injection of NPY (0.2 mg/kg BW in artificial cerebrospinal fluid; aCSF, synthetic Y1 receptor antagonist GR231118 (0.5 mg/kg BW in aCSF or vehicle (aCSF, or an i.v. injection of PYY3-36 (0.5 mg/kg BW in PBS or vehicle (PBS. RESULTS: Administration of NPY into both the LV and 3V increased food intake within one hour after injection (+164%, p<0.001 and +367%, p<0.001, respectively. NPY administration neither in the LV nor in the 3V affected hepatic VLDL-TG or VLDL-apoB production. Likewise, antagonizing central NPY signaling by either PYY3-36 or GR231118 administration did not affect hepatic VLDL production. CONCLUSION: In mice, as opposed to rats, acute central administration of NPY increases food intake without affecting hepatic VLDL production. These results are of great significance when extrapolating findings on the central regulation of hepatic VLDL production between species.

  9. Study of different 3-aminopropyl triethoxysilane (APTES) concentration on TiO2 particles based IDE for cervical cancer detection

    Science.gov (United States)

    Raqeema, S.; Hashim, U.; Azizah, N.; Nadzirah, Sh.; Arshad, M. K. Md; Ruslinda, A. R.; Gopinath, Subash C. B.

    2017-03-01

    HPV that also called Human Papillomaviruses is the major cause of the cervical cancer. HPV 16 and HPV 18 are the two types of HPV are the most HPV-associated cancers and responsible as a high-risk HPV. Cervical cancer taken about 70 percent of all cases due HPV infections. Cervical malignancy for the most part development on a lady's cervix and its was developed slowly as cancer disease. TiO2 particles give better performance and low cost of the biosensor. The used of 3-aminopropyl triethoxysilane (APTES) will be more efficient for DNA nanochip. APTES used as absorption reaction to immobilize organic biomolecules on the inorganic surface. Besides, APTES give better functionalization of the adsorption mechanism on IDE. The surface functionalized for immobilizing the DNA, which is the combination of the DNA probe and the HPV target produce high sensitivity andfast detection of the IDE. The Current-Voltage (IV) characteristic proved the sensitivity of the DNA nanochip increase as the concentration varied from 0% concentration to 24% of APTES concentration.

  10. Observations of the aerosol particle number concentration in the marine boundary layer over the south-eastern Baltic Sea

    Directory of Open Access Journals (Sweden)

    Dalia Jasinevičiene

    2013-08-01

    Full Text Available Continuous measurements of the aerosol particle number concentration (PNCin the size range from 4.5 nm to 2 µm were performed at the Preila marine background site during 2008–2009.The concentration maxima in summer was twice the average (2650±50 cm-3. A trajectory-based approach was applied for source identification. Potential Source Contribution Function (PSCFanalysis was performed to estimate the possible contribution of long-range andlocal PNC transport to PNC concentrations recorded at the marine backgroundsite. The PSCF results showed that the marine boundary layer was not seriouslyaffected by long-range transport, but that local transport of air pollutionwas recognized as an important factor. North Atlantic and Sea-Marine typeclusters respectively represented 32.1% and 17.9% of the total PNC spectraand were characterized by the lowest PNCs (1080±1340 and 1210±1040 cm-3 respectively among all clusters.   Wavelet transformation analysis of 1-h aerosol PNC indicated that whilethe 16-h scale was a constant feature of aerosol PNC evolution in spring, the longer (∼60-h scalesappeared mainly over the whole year (except June. Principal componentanalysis (PCA revealed a strong correlation between PNC and NaCl,highlighting the influence of sea-salt aerosols. In addition, PCA also showedthat PNC depended on optical and meteorological parameters such as UVR andtemperature.

  11. Variability of levels of PM, black carbon and particle number concentration in selected European cities

    Directory of Open Access Journals (Sweden)

    C. Reche

    2011-03-01

    Full Text Available In many large cities of Europe standard air quality limit values of particulate matter (PM are exceeded. Emissions from road traffic and biomass burning are frequently reported to be the major causes. As a consequence of these exceedances a large number of air quality plans, most of them focusing on traffic emissions reductions, have been implemented in the last decade. In spite of this implementation, a number of cities did not record a decrease of PM levels. Thus, is the efficiency of air quality plans overestimated? Or do we need a more specific metric to evaluate the impact of the above emissions on the levels of urban aerosols?

    This study shows the results of the interpretation of the 2009 variability of levels of PM, black carbon (BC, aerosol number concentration (N and a number of gaseous pollutants in seven selected urban areas covering road traffic, urban background, urban-industrial, and urban-shipping environments from southern, central and northern Europe.

    The results showed that variations of PM and N levels do not always reflect the variation of the impact of road traffic emissions on urban aerosols. However, BC levels vary proportionally with those of traffic related gaseous pollutants, such as CO, NO2 and NO. Due to this high correlation, one may suppose that monitoring the levels of these gaseous pollutants would be enough to extrapolate exposure to traffic-derived BC levels. However, the BC/CO, BC/NO2 and BC/NO ratios vary widely among the cities studied, as a function of distance to traffic emissions, vehicle fleet composition and the influence of other emission sources such as biomass burning. Thus, levels of BC should be measured at air quality monitoring sites.

    During traffic rush hours, a narrow variation in the N/BC ratio was evidenced, but a wide variation of this ratio was determined for the noon period. Although in central and northern Europe N and BC levels tend to vary

  12. Effect of flexibility on the growth of concentration fluctuations in a suspension of sedimenting fibers: Particle simulations

    Energy Technology Data Exchange (ETDEWEB)

    Manikantan, Harishankar; Saintillan, David [Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093 (United States)

    2016-01-15

    Three-dimensional numerical simulations are performed to study the stability of a sedimenting suspension of weakly flexible fibers. It is well known that a suspension of rigid rods sedimenting under gravity at low Reynolds number is unstable to concentration fluctuations owing to hydrodynamic interactions. Flexible fibers, however, reorient while settling and even weak flexibility can alter their collective dynamics. In our recent work [Manikantan et al., “The instability of a sedimenting suspension of weakly flexible fibres,” J. Fluid Mech. 756, 935–964 (2014)], we developed a mean-field theory to predict the linear stability of such a system. Here, we verify these predictions using accurate and efficient particle simulations based on a slender-body model. We also demonstrate the mechanisms by which flexibility-induced reorientation alters suspension microstructure, and through it, its stability. Specifically, we first show that the anisotropy of the base state in the case of a suspension of flexible fibers has a destabilizing effect compared to a suspension of rigid rods. Second, a conflicting effect of flexibility is also shown to suppress particle clustering and slow down the growth of the instability. The relative magnitude of filament flexibility and rotational Brownian motion dictates which effect dominates, and our simulations qualitatively follow theoretically predicted trends. The mechanism for either effects is tied to the flexibility-induced reorientation of particles, which we illustrate using velocity and orientation statistics from our simulations. Finally, we also show that, in the case of an initially homogeneous and isotropic suspension, flexibility always acts to suppress the growth of the instability.

  13. Effect of Concentration and Surface Property of Silica Sol on the Determination of Particle Size and Electrophoretic Mobility by Light Scattering Method

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Gyeong Sook; Lee, Dong-Hyun; Kim, Dae Sung; Lim, Hyung Mi; Lee, Seung-Ho [Korea Institute of Ceramic Engineering Technology (KICET), Seoul (Korea, Republic of); Kim, Chong youp [Korea University, Seoul (Korea, Republic of)

    2013-10-15

    Colloidal silica is used in various industrial products such as chemical mechanical polishing slurry for planarization of silicon and sapphire wafer, organic-inorganic hybrid coatings, binder of investment casting, etc. An accurate determination of particle size and dispersion stability of silica sol is demanded because it has a strong influence on surface of wafer, film of coatings or bulks having mechanical, chemical and optical properties. The study herein is discussed on the effect of measurement results of average particle size, sol viscosity and electrophoretic mobility of particle according to the volume fraction of eight types of silica sol with different size and surface properties of silica particles which are presented by the manufacturer. The measured particle size and the mobility of these sol were changed by volume fraction or particle size due to highly active surface of silica particle and change of concentration of counter ion by dilution of silica sol. While in case the measured sizes of small particles less than 60 nm are increased with increasing volume fraction, the measured sizes of larger particles than 60 nm are slightly decreased. The mobility of small particle such as 12 nm are decreased with increase of viscosity. However, the mobility of 100 nm particles under 0.048 volume fraction are increased with increasing volume fraction and then decreased over higher volume fraction.

  14. A pilot investigation into associations between indoor airborne fungal and non-biological particle concentrations in residential houses in Brisbane, Australia.

    Science.gov (United States)

    Hargreaves, Megan; Parappukkaran, Sandhya; Morawska, Lidia; Hitchins, Jane; He, Congrong; Gilbert, Dale

    2003-08-01

    Indoor air contains a complex mixture of bioaerosols such as fungi, bacteria and allergens, as well as non-biological particles including products from various combustion processes. To date little work has been done to investigate the interactions and associations between particles of biological and non-biological origin, however, any occurring interactions could affect pollutant behaviour in the air and ultimately the effect they have on health. The aim of this work was to examine associations between the concentration levels of airborne particles and fungi measured in 14 residential suburban houses in Brisbane. The most frequently isolated fungal genus was Cladosporium, Curvularia, Alternaria, Fusarium and Penicillium. The average outdoor and indoor (living room) concentrations of fungal colony forming units were 1133+/-759 and 810+/-389, respectively. Average outdoor and indoor (normal ventilation) concentrations of submicrometre and supermicrometre particles were 23.8 x 10(3) and 21.7 x 10(3) (particles/cm(3)), 1.78 and 1.74 (particles/cm(3)), respectively. The study showed that no statistically significant associations between the fungal spore and submicrometre particle concentrations or PM(2.5) were present, while a weak but statistically significant relationship was found between fungal and supermicrometre particle concentrations (for the outdoors R(2)=0.4, P=0.03 and for a living room R(2)=0.3, P=0.04). A similarity in behaviour between the submicrometre particle and fungal spore concentrations was that the fungal spore concentrations were related directly to the distance from the source (a nearby park), in a very similar way in which the submicrometre particles originating from vehicle emissions from a road, were dependent on the distance to the road. In the immediate proximity to the park, fungal concentrations rose up to approximately 3100 CFU/m(3), whereas for houses more than 150 m away from the park the concentrations of fungi were below 1000 CFU/m(3

  15. Concentration and size distribution of particulate oxalate in marine and coastal atmospheres - Implication for the increased importance of oxalate in nanometer atmospheric particles

    Science.gov (United States)

    Guo, Tianfeng; Li, Kai; Zhu, Yujiao; Gao, Huiwang; Yao, Xiaohong

    2016-10-01

    In literature, particulate oxalate has been widely studied in the total suspended particles (TSP), particles 100 nm. In this article, we measured oxalate's concentrations in size-segregated atmospheric particles down to 10 nm or 56 nm during eight campaigns performed at a semi-urban coastal site, over the marginal seas of China and from the marginal seas to the northwest Pacific Ocean (NWPO) in 2012-2015. When the sum of the oxalate's concentration in particles pollution event. Mode analysis results of particulate oxalate and the correlation between oxalate and sulfate suggested that the elevated concentrations of oxalate in PM10 were mainly related to enhanced in-cloud formation of oxalate via anthropogenic precursors. Size distribution data in the total of 136 sets of samples also showed approximately 80% of particulate oxalate's mass existing in atmospheric particles >100 nm. Consistent with previous studies, particulate oxalate in particles >100 nm was a negligible ionic component when comparing to particulate SO42- in the same size range. However, the mole ratios of oxalate/sulfate in particles 100 nm atmospheric particles such as PM2.5, PM10, TSP, etc.

  16. A comparison of strategies for estimation of ultrafine particle number concentrations in urban air pollution monitoring networks.

    Science.gov (United States)

    Reggente, Matteo; Peters, Jan; Theunis, Jan; Van Poppel, Martine; Rademaker, Michael; De Baets, Bernard; Kumar, Prashant

    2015-04-01

    We propose three estimation strategies (local, remote and mixed) for ultrafine particles (UFP) at three sites in an urban air pollution monitoring network. Estimates are obtained through Gaussian process regression based on concentrations of gaseous pollutants (NOx, O3, CO) and UFP. As local strategy, we use local measurements of gaseous pollutants (local covariates) to estimate UFP at the same site. As remote strategy, we use measurements of gaseous pollutants and UFP from two independent sites (remote covariates) to estimate UFP at a third site. As mixed strategy, we use local and remote covariates to estimate UFP. The results suggest: UFP can be estimated with good accuracy based on NOx measurements at the same location; it is possible to estimate UFP at one location based on measurements of NOx or UFP at two remote locations; the addition of remote UFP to local NOx, O3 or CO measurements improves models' performance.

  17. Dissipative particle dynamics simulation of flow generated by two rotating concentric cylinders: II. Lateral dissipative and random forces

    Energy Technology Data Exchange (ETDEWEB)

    Filipovic, N [Faculty of Mechanical Engineering, University of Kragujevac (Serbia); Haber, S [Technion-Israel Institute of Technology, Haifa (Israel); Kojic, M [Faculty of Mechanical Engineering, University of Kragujevac (Serbia); Tsuda, A [Harvard School of Public Health, Harvard University, Boston, MA (United States)

    2008-02-07

    Traditional DPD methods address dissipative and random forces exerted along the line connecting neighbouring particles. Espanol (1998 Phys. Rev. E 57 2930-48) suggested adding dissipative and random force components in a direction perpendicular to this line. This paper focuses on the advantages and disadvantages of such an addition as compared with the traditional DPD method. Our benchmark system comprises fluid initially at rest occupying the space between two concentric cylinders rotating with various angular velocities. The effect of the lateral force components on the time evolution of the simulated velocity profile was also compared with that of the known analytical solution. The results show that (i) the solution accuracy at steady state has improved and the error has been reduced by at least 30% (in one case by 75%), (ii) the DPD time to reach steady state has been halved, (iii) the CPU time has increased by only 30%, and (iv) no significant differences exist in density and temperature distributions.

  18. Dissipative particle dynamics simulation of flow generated by two rotating concentric cylinders: II. Lateral dissipative and random forces

    Science.gov (United States)

    Filipovic, N.; Haber, S.; Kojic, M.; Tsuda, A.

    2008-02-01

    Traditional DPD methods address dissipative and random forces exerted along the line connecting neighbouring particles. Espanol (1998 Phys. Rev. E 57 2930-48) suggested adding dissipative and random force components in a direction perpendicular to this line. This paper focuses on the advantages and disadvantages of such an addition as compared with the traditional DPD method. Our benchmark system comprises fluid initially at rest occupying the space between two concentric cylinders rotating with various angular velocities. The effect of the lateral force components on the time evolution of the simulated velocity profile was also compared with that of the known analytical solution. The results show that (i) the solution accuracy at steady state has improved and the error has been reduced by at least 30% (in one case by 75%), (ii) the DPD time to reach steady state has been halved, (iii) the CPU time has increased by only 30%, and (iv) no significant differences exist in density and temperature distributions.

  19. 微细粒重选技术研究%A Study of the Gravity Concentration Technology on Superfine Particles

    Institute of Scientific and Technical Information of China (English)

    魏镜弢; 杨波

    2001-01-01

    The effective method of recovering superfine heavy mineral is a new saperfine gravity equipment being developed.Recovering superfine particle in centrifugal field can strengthen the effect of separation.This paper introduces the feature of MGS,Knelson concentrator and superfine centrifugal jigger.To counter the deficiency of superfine gravity equipment available,it goes further into the train of thought of gravity concetration technology on superfine particle.%微细粒重选设备的开发,是回收微细粒重矿物的有效方法.在高心力场内回收微细粒颗粒,可强化分选效果.分别介绍了多重力分选机、Knelson选矿机、微细粒离心跳汰机的特点.针对现有细粒重选设备的不足之处,探讨了微细粒重选的发展思路.

  20. Spatial variations in ambient ultrafine particle concentrations and the risk of incident prostate cancer: A case-control study.

    Science.gov (United States)

    Weichenthal, Scott; Lavigne, Eric; Valois, Marie-France; Hatzopoulou, Marianne; Van Ryswyk, Keith; Shekarrizfard, Maryam; Villeneuve, Paul J; Goldberg, Mark S; Parent, Marie-Elise

    2017-07-01

    Diesel exhaust contains large numbers of ultrafine particles (UFPs, hospitals in the Montreal area between 2005 and 2009. Population controls were identified from provincial electoral lists of French Montreal residents and frequency-matched to cases using 5-year age groups. UFP exposures were estimated using a land use regression model. Exposures were assigned to residential locations at the time of diagnosis/recruitment as well as approximately 10-years earlier to consider potential latency between exposure and disease onset. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated per interquartile range (IQR) increase in UFPs (approximately 4000 particles/cm(3)) using logistic regression models adjusting for individual-level and ecological covariates. Ambient UFP concentrations were associated with an increased risk of prostate cancer (OR=1.10, 95% CI: 1.01, 1.19) in fully adjusted models when exposures were assigned to residences 10-years prior to diagnosis. This risk estimate increased slightly (OR=1.17, 95% CI; 1.01, 1.35) when modeled as a non-linear natural spline function. A smaller increased risk (OR=1.04, 95% CI: 0.97, 1.11) was observed when exposures were assigned to residences at the time of diagnosis. Exposure to ambient UFPs may increase the risk of prostate cancer. Future studies are needed to replicate this finding as this is the first study to evaluate this relationship. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

  1. Elevated Concentrations of Lead in Particulate Matter on the Neighborhood-Scale in Delhi, India As Determined by Single Particle Analysis.

    Science.gov (United States)

    Shen, Hongru; Peters, Thomas M; Casuccio, Gary S; Lersch, Traci L; West, Roger R; Kumar, Amit; Kumar, Naresh; Ault, Andrew P

    2016-05-17

    High mass concentrations of atmospheric lead particles are frequently observed in the Delhi, India metropolitan area, although the sources of lead particles are poorly understood. In this study, particles sampled across Delhi (August - December 2008) were analyzed by computer-controlled scanning electron microscopy with energy dispersive X-ray spectroscopy (CCSEM-EDX) to improve our understanding of the spatial and physicochemical variability of lead-rich particles (>90% lead). The mean mass concentration of lead-rich particles smaller than 10 μm (PM10) was 0.7 μg/m(3) (1.5 μg/m(3) std. dev.) with high variability (range: 0-6.2 μg/m(3)). Four samples (16% of 25 samples) with PM10 lead-rich particle concentrations >1.4 μg/m(3) were defined as lead events and studied further. The temporal characteristics, heterogeneous spatial distribution, and wind patterns of events, excluded regional monsoon conditions or common anthropogenic sources from being the major causes of the lead events. Individual particle composition, size, and morphology analysis indicate informal recycling operations of used lead-acid batteries as the likely source of the lead events. This source is not typically included in emission inventories, and the observed isolated hotspots with high lead concentrations could represent an elevated exposure risk in certain neighborhoods of Delhi.

  2. Evolution of particle properties and trace gas concentrations at the top of the Mexico City boundary layer

    Science.gov (United States)

    Raga, G.; Baumgardner, D.; Grutter, M.; Santos, B. T.; Moya, C. O.; Allan, J.

    2006-12-01

    The Altzomoni ridge is located in the Cortez Pass, in a national park, between the volcanoes of Iztaccihuatl and Popocatepetl, at an altitude of 4010 m, and 60 km to the SE of the center of Mexico City. This region is isolated from local emissions from combustion yet there is a daily incursion of pollution from either the Mexico City basin, when winds are from the west or from the Puebla valley when winds are from the east. This was the motivation for setting up instruments at this site to measure the concentrations of trace gases and the physical, chemical and optical properties of aerosol particles. A 12 m tower was also erected to measure fluxes of momentum, heat, condensation nuclei (CN) and CO2. Measurements were begun during the last week of November, 2005 and continued until early June, 2006. The concentrations of CN, CO2 and CO clearly indicate that the site is in the free troposphere at night and early morning, but the regional boundary layer grows to altitudes above the site every day. Hence, this site is ideal for making observations of atmospheric chemistry at the interface between rural and urban regions. The preliminary analyses have shown that the "free tropospheric" values of CN, particle bound polycyclic aromatic hydrocarbons (PPAH) and black carbon (BC) rarely decrease below 1000 cm-3, 4 ng m-3, 100 ng m-3, respectively, suggesting the presence of a residual layer of contaminants. Nighttime CO and O3 are usually above 0.1 and 0.05 ppm. The CO concentration at the measurement site is a tenth of the Mexico City value and reached its maximum approximately six hours after the maximum in the city center. The maximum O3 in Mexico City and Altzomoni are frequently the same concentration but with no repeatable pattern in the phase differences. The highly linear relationship between BC and CO reflects the removal and dilution processes, i.e. the average ratio between BC and CO in Mexico City is 1000:1 whereas it is 3000:1 in Altzomoni. This relationship

  3. Evolution of trace gas concentrations and the chemical properties of particles at the top of the Mexico City boundary layer.

    Science.gov (United States)

    Ochoa, C.; Baumgardner, D.; Grutter, M.

    2007-05-01

    The Altzomoni ridge is located in the Cortez Pass, in a national park, between the volcanoes of Iztaccíhuatl and Popocatépetl, at an altitude of 4010 m, and 60 km to the SE of the center of Mexico City. This region is isolated from local emissions from combustion yet there is a daily incursion of pollution from either the Mexico City basin, when winds are from the west or from the Puebla valley when winds are from the east. This was the motivation for setting up instruments at this site to measure the concentrations of trace gases and the physical, chemical and optical properties of aerosol particles. Measurements were begun during the last week of November, 2005 and continued until early June, 2006. The concentrations of CN, CO2 and CO clearly indicate that the site is in the free troposphere at night and early morning, but the regional boundary layer grows to altitudes above the site every day. Hence, this site is ideal for making observations of atmospheric chemistry at the interface between rural and urban regions. The preliminary analyses have shown that the "free tropospheric" values of CN, particle bound polycyclic aromatic hydrocarbons (PPAH) and black carbon (BC) rarely decrease below 1000 cm-3, 4 ng m-3, 100 ng m-3, respectively, suggesting the presence of a residual layer of contaminants. Nighttime CO and O3 are usually above 0.1 and 0.05 ppm. The CO concentration at the measurement site is a tenth of the Mexico City value and reached its maximum approximately six hours after the maximum in the city center. The maximum O3 in Mexico City and Altzomoni are frequently the same concentration but with no repeatable pattern in the phase differences. The highly linear relationship between BC and CO reflects the removal and dilution processes, i.e. the average ratio between BC and CO in Mexico City is 1000:1 whereas it is 3000:1 in Altzomoni. This relationship also depends on the origin of the boundary layer air, i.e. whether it comes from the east or west

  4. Temperature dependence of the particle/gas partition coefficient: An application to predict indoor gas-phase concentrations of semi-volatile organic compounds.

    Science.gov (United States)

    Wei, Wenjuan; Mandin, Corinne; Blanchard, Olivier; Mercier, Fabien; Pelletier, Maud; Le Bot, Barbara; Glorennec, Philippe; Ramalho, Olivier

    2016-09-01

    The indoor gas-phase concentrations of semi-volatile organic compounds (SVOCs) can be predicted from their respective concentrations in airborne particles by applying the particle/gas partitioning equilibrium. The temperature used for partitioning is often set to 25°C. However, indoor temperatures frequently differ from this reference value. This assumption may result in errors in the predicted equilibrium gas-phase SVOC concentrations. To improve the prediction model, the temperature dependence of the particle/gas partition coefficient must be addressed. In this paper, a theoretical relationship between the particle/gas partition coefficient and temperature was developed based on the SVOC absorptive mechanism. The SVOC particle/gas partition coefficients predicted by employing the derived theoretical relationship agree well with the experimental data retrieved from the literature (R>0.93). The influence of temperature on the equilibrium gas-phase SVOC concentration was quantified by a dimensionless analysis of the derived relationship between the SVOC particle/gas partition coefficient and temperature. The predicted equilibrium gas-phase SVOC concentration decreased by between 31% and 53% when the temperature was lowered by 6°C, while it increased by up to 750% when the indoor temperature increased from 15°C to 30°C.

  5. Temperature dependence of the particle/gas partition coefficient: An application to predict indoor gas-phase concentrations of semi-volatile organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Wenjuan, E-mail: Wenjuan.Wei@cstb.fr [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); Mandin, Corinne [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); Blanchard, Olivier [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Mercier, Fabien [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Pelletier, Maud [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Le Bot, Barbara [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); and others

    2016-09-01

    The indoor gas-phase concentrations of semi-volatile organic compounds (SVOCs) can be predicted from their respective concentrations in airborne particles by applying the particle/gas partitioning equilibrium. The temperature used for partitioning is often set to 25 °C. However, indoor temperatures frequently differ from this reference value. This assumption may result in errors in the predicted equilibrium gas-phase SVOC concentrations. To improve the prediction model, the temperature dependence of the particle/gas partition coefficient must be addressed. In this paper, a theoretical relationship between the particle/gas partition coefficient and temperature was developed based on the SVOC absorptive mechanism. The SVOC particle/gas partition coefficients predicted by employing the derived theoretical relationship agree well with the experimental data retrieved from the literature (R > 0.93). The influence of temperature on the equilibrium gas-phase SVOC concentration was quantified by a dimensionless analysis of the derived relationship between the SVOC particle/gas partition coefficient and temperature. The predicted equilibrium gas-phase SVOC concentration decreased by between 31% and 53% when the temperature was lowered by 6 °C, while it increased by up to 750% when the indoor temperature increased from 15 °C to 30 °C. - Highlights: • A theoretical relationship between K{sub p} and temperature was developed. • The relationship was based on the SVOC absorptive mechanism. • The temperature impact was quantified by a dimensionless analysis.

  6. Increased large VLDL and small LDL particles are related to lower bilirubin in Type 2 diabetes mellitus

    NARCIS (Netherlands)

    Dullaart, Robin P F; de Vries, Rindert; Lefrandt, Joop D

    2014-01-01

    OBJECTIVES: Bilirubin may protect against atherosclerotic cardiovascular disease by virtue of its anti-oxidative properties, but lower bilirubin may also be associated to atherogenic lipoprotein abnormalities. We determined associations of plasma (apo)lipoproteins and lipoprotein subfractions in sub

  7. Increased large VLDL and small LDL particles are related to lower bilirubin in Type 2 diabetes mellitus

    NARCIS (Netherlands)

    Dullaart, Robin P F; de Vries, Rindert; Lefrandt, Joop D

    2014-01-01

    OBJECTIVES: Bilirubin may protect against atherosclerotic cardiovascular disease by virtue of its anti-oxidative properties, but lower bilirubin may also be associated to atherogenic lipoprotein abnormalities. We determined associations of plasma (apo)lipoproteins and lipoprotein subfractions in

  8. Hepatic VLDL production in ob/ob mice is not stimulated by massive de novo lipogenesis but is less sensitive to the suppressive effects of insulin.

    Science.gov (United States)

    Wiegman, Coen H; Bandsma, Robert H J; Ouwens, Margriet; van der Sluijs, Fjodor H; Havinga, Rick; Boer, Theo; Reijngoud, Dirk-Jan; Romijn, Johannes A; Kuipers, Folkert

    2003-05-01

    Type 2 diabetes in humans is associated with increased de novo lipogenesis (DNL), increased fatty acid (FA) fluxes, decreased FA oxidation, and hepatic steatosis. In this condition, VLDL production is increased and resistant to suppressive effects of insulin. The relationships between hepatic FA metabolism, steatosis, and VLDL production are incompletely understood. We investigated VLDL-triglyceride and -apolipoprotein (apo)-B production in relation to DNL and insulin sensitivity in female ob/ob mice. Hepatic triglyceride (5-fold) and cholesteryl ester (15-fold) contents were increased in ob/ob mice compared with lean controls. Hepatic DNL was increased approximately 10-fold in ob/ob mice, whereas hepatic cholesterol synthesis was not affected. Basal rates of hepatic VLDL-triglyceride and -apoB100 production were similar between the groups. Hyperinsulinemic clamping reduced VLDL-triglyceride and -apoB100 production rates by approximately 60% and approximately 75%, respectively, in lean mice but only by approximately 20% and approximately 20%, respectively, in ob/ob mice. No differences in hepatic expression of genes encoding apoB and microsomal triglyceride transfer protein were found. Hepatic expression and protein phosphorylation of insulin receptor and insulin receptor substrate isoforms were reduced in ob/ob mice. Thus, strongly induced hepatic DNL is not associated with increased VLDL production in ob/ob mice, possibly related to differential hepatic zonation of apoB synthesis (periportal) and lipid accumulation (perivenous) and/or relatively low rates of cholesterogenesis. Insulin is unable to effectively suppress VLDL-triglyceride production in ob/ob mice, presumably because of impaired insulin signaling.

  9. Source apportionment of fine PM and sub-micron particle number concentrations at a regional background site in the western Mediterranean: a 2.5 year study

    Science.gov (United States)

    Cusack, M.; Pérez, N.; Pey, J.; Alastuey, A.; Querol, X.

    2013-05-01

    The chemical composition and sources of ambient fine particulate matter (PM1) over a period of 2.5 years for a regional background site in the western Mediterranean are presented in this work. Furthermore, sub-micron particle number concentrations and the sources of these particles are also presented. The mean PM1 concentration for the measurement period was 8.9 μg m-3, with organic matter (OM) and sulphate comprising most of the mass (3.2 and 1.5 μg m-3 respectively). Six sources were identified in PM1 by Positive Matrix Factorisation (PMF): secondary organic aerosol, secondary nitrate, industrial, traffic + biomass burning, fuel oil combustion and secondary sulphate. Typically anthropogenic sources displayed elevated concentrations during the week with reductions at weekends. Nitrate levels were elevated in winter and negligible in summer, whereas secondary sulphate levels underwent a contrasting seasonal evolution with highest concentrations in summer, similar to the fuel oil combustion source. The SOA source was influenced by episodes of sustained pollution as a result of anticyclonic conditions occurring during winter, giving rise to thermal inversions and the accumulation of pollutants in the mixing layer. Increased levels in summer were owing to higher biogenic emissions and regional recirculation of air masses. The industrial source decreased in August due to decreased emissions during the vacation period. Increases in the traffic + biomass burning source were recorded in January, April and October, which were attributed to the occurrence of the aforementioned pollution episodes and local biomass burning emission sources, which include agriculture and domestic heating systems. Average particle number concentrations (N9-825 nm) from 5/11/2010 to 01/06/2011 and from 15/10/2011 to 18/12/2011 reached 3097 cm-3. Five emission sources of particle of sub-micron particles were determined by Principal Component Analysis (PCA); industrial + traffic + biomass

  10. Factors influencing particle number concentrations, size distributions and modal parameters at a roof-level and roadside site in Leicester, UK.

    Science.gov (United States)

    Agus, Emily L; Young, David T; Lingard, Justin J N; Smalley, Robert J; Tate, James E; Goodman, Paul S; Tomlin, Alison S

    2007-11-01

    Measurements of urban particle number concentrations and size distributions in the range 5-1000 nm were taken at elevated (roof-level) and roadside sampling sites on Narborough Road in Leicester, UK, along with simultaneous measurements of traffic, NO(x), CO and 1,3-butadiene concentrations and meteorological parameters. A fitting program was used to determine the characteristics of up to five modal groups present in the particle size distributions. All particle modal concentrations peaked during the morning and evening rush hours. Additional events associated with the smallest mode, that were not observed to be connected to primary emissions, were also present suggesting that this mode consisted of newly formed secondary particles. These events included peaks in concentration which coincided with peaks in solar radiation, and lower concentrations of the larger modes. Investigation into the relationships between traffic flow and occupancy indicated three flow regimes; free-flow, unstable and congested. During free-flow conditions, positive linear relationships existed between traffic flow and particle modal number concentrations. However, during unstable and congested periods, this relationship was shown to break-down. Similar trends were observed for concentrations of the gas phase pollutants NO(x), CO and 1,3-butadiene. Strong linear relationships existed between NO(x), CO, 1,3-butadiene concentrations, nucleation and Aitken mode concentrations at both sampling locations, indicating a local traffic related emission source. At the roadside, both nucleation and Aitken mode are best represented by a decreasing exponential function with wind speed, whereas at the roof-level this relationship only occurred for Aitken mode particles. The differing relationships at the two sampling locations are most likely due to a combination of meteorological factors and distance from the local emission source.

  11. O/W emulsions stabilised by both low molecular weight surfactants and colloidal particles: The effect of surfactant type and concentration.

    Science.gov (United States)

    Pichot, R; Spyropoulos, F; Norton, I T

    2010-12-01

    The stability against coalescence of O/W emulsions in the presence of both surfactants and colloidal particles was investigated. In particular the effect of the surfactant type and concentration in these emulsifier mixtures on the O/W emulsions' stability was studied. Two types of surfactants were selected; those that have the ability to stabilise O/W emulsions on their own (O/W surfactants) and those that cannot (W/O surfactants). Tween 60 and Sodium Caseinate were selected as the O/W surfactants and lecithin as the W/O surfactant. Oil-in-water emulsions prepared with both particles and any of the three surfactants were stable against coalescence but, depending on the type of surfactant, the behaviour of the systems was found to depend on surfactant concentration. The droplet sizes of emulsions stabilised by mixed emulsifier systems containing low concentrations of O/W surfactants (Tween 60 or Sodium Caseinate) were smaller than those solely stabilised by either the surfactant or particles alone. At intermediate O/W surfactants concentrations, the droplet sizes of the emulsions increased. Further increases in the O/W surfactants' concentration, resulted in the complete removal of particles from the interface with the system now behaving as a surfactant-only stabilised emulsion. The behaviour of emulsions stabilised by emulsifier mixtures containing W/O surfactants was not dependent on the concentration of surfactant: no removal of particles was observed. Copyright © 2010 Elsevier Inc. All rights reserved.

  12. Land use regression models for total particle number concentrations using 2D, 3D and semantic parameters

    Science.gov (United States)

    Ghassoun, Yahya; Löwner, Marc-Oliver

    2017-10-01

    Total particle number concentration (TNC) was studied in a 1 × 2 km area in Berlin, the capital of Germany by three Land Use Regression models (LUR). The estimation of TNC was established and compared using one 2D-LUR and two 3D-LUR models. All models predict total number concentrations TNC by using urban morphological (2D resp. 3D) and additional semantical parameters. 2D and semantical parameters were derived from Open Street Map data (OSM) whereas 3D parameters were derived from a CityGML-based 3D city model. While the models are capable to depict the spatial variation of TNC across the study area, the two 3D-LUR showed better results than the 2D-LUR. The 2D-LUR model explained 74% of the variance of TNC for the full data set with root mean square error (RMSE) of 4014 cm-3 while the 3D-LUR explained 79% of the variance with an RMSE of 3477 cm-3. The further introduction of a new spatial parameter, the Frontal Area Index (FAI) that represents the dynamic factor wind direction enhanced the 3D-LUR to explain 82% of the variance with RMSE of 3389 cm-3. Furthermore, the semantical parameters (e.g. streets type) played a significant role in all models.

  13. The application of the boundary element method in BEM++ to small extreme Chebyshev ice particles and the remote detection of the ice crystal number concentration of small atmospheric ice particles

    Science.gov (United States)

    Baran, Anthony J.; Groth, Samuel P.

    2017-09-01

    The measurement of the shape and size distributions of small atmospheric ice particles (i.e. less than about 100 μm in size) is still an unresolved problem in atmospheric physics. This paper is composed of two parts, each addressing one of these measurements. In the first part, we report on an application of a new open-source electromagnetic boundary element method (BEM) called ;BEM++; to characterise the shape of small ice particles through the simulation of the two-dimensional (2D) light scattering patterns of extreme Chebyshev ice particles. Previous electromagnetic studies of Chebyshev particles have concentrated upon high Chebyshev orders, but with low Chebyshev deformation parameters. Here, we extend such studies by concentrating on the 2D light scattering properties of Chebyshev particles with extreme deformation parameters, up to 0.5, and with Chebyshev orders up to 16, at a size parameter of 15, in a fixed orientation. The results demonstrate the applicability of BEM++ to the study of the electromagnetic scattering properties of extreme particles and the usefulness of measuring the light scattering patterns of particles in 2D to mimic the scattering behaviours of highly irregular particles, such as dendritic atmospheric ice or hazardous biological and/or aerosol particles. In the second part, we demonstrate the potential application of remotely sensed very-high-resolution brightness temperature measurements of optically thin cirrus between wavelengths of about 8.0 and 12.0 μm to resolve the current atmospheric physics issue of determining the number concentration of small ice particles with size less than about 100 μm.

  14. Evaluation of building characteristics in 27 dwellings in Denmark and the effect of using particle filtration units on PM2.5 concentrations

    DEFF Research Database (Denmark)

    Spilak, Michal P.; Loft, Steffen

    2014-01-01

    Exposure to airborne particulate matter in homes is associated with the risk of cardiovascular diseases and respiratory problems. Due to the extended time people spend at home, reducing the particle concentration in homes may be a means to reduce the risk of cardiovascular diseases and respiratory...... problems. Use of particle filtration units (PFU's) might be an effective way for rapid removal of indoor PM.In a randomised cross-over design, the custom built PFU's ran for two weeks in each of two modes: with or without the inclusion of a HEPA filter.We assessed the association between the concentration...... concentrations. Furthermore, the winter period and a location farther from a trafficked street were associated with increased PM2.5 mass. Overall, the use of PFU led to a decrease in the concentrations of PM2.5 of 54.5% (median value).We assessed the PFU particle-removal efficiency by using the amount...

  15. Concentration of Bacterial Aerosols Associated with Particles: Observations at a Southwestern Coastal Site of Japan in the Spring of 2013-2014

    Science.gov (United States)

    Murata, K.; Zhang, D.

    2015-12-01

    Airborne bacteria are the major group of bioaerosols in the air and are considered to have important climate effects by acting as ice nuclei. To investigate the dependence of bacteria on particles in the air, we enumerated bacterial cells in size-segregated airborne particle samples that were collected at a rural seaside site on the southwestern coast of Japan during dust and non-dust periods in the spring of 2013-2014. Proportion of particle-attached bacteria was 75-84% of total airborne bacterial concentration during dust periods and 27-76% during non-dust periods, both of which were equal to approximately 12% of >1 µm aerosol particle concentrations. The concentration of particle-attached bacteria was 3.2 times higher during dust periods, compared with that during non-dust periods. The viability, which is referring to the ratio of viable cells to total cells, of particle-attached bacteria was 33-82% during dust periods and 45-98% during non-dust periods. The predominance of particle-associated viable/non-viable bacteria during dust periods demonstrates a potential of bacteria to cooperate with dust in influencing the climate, ecosystems, and health where they arrive.

  16. Occupational Exposure to Cobalt and Tungsten in the Swedish Hard Metal Industry: Air Concentrations of Particle Mass, Number, and Surface Area

    Science.gov (United States)

    Bryngelsson, Ing-Liss; Pettersson, Carin; Husby, Bente; Arvidsson, Helena; Westberg, Håkan

    2016-01-01

    Exposure to cobalt in the hard metal industry entails severe adverse health effects, including lung cancer and hard metal fibrosis. The main aim of this study was to determine exposure air concentration levels of cobalt and tungsten for risk assessment and dose–response analysis in our medical investigations in a Swedish hard metal plant. We also present mass-based, particle surface area, and particle number air concentrations from stationary sampling and investigate the possibility of using these data as proxies for exposure measures in our study. Personal exposure full-shift measurements were performed for inhalable and total dust, cobalt, and tungsten, including personal real-time continuous monitoring of dust. Stationary measurements of inhalable and total dust, PM2.5, and PM10 was also performed and cobalt and tungsten levels were determined, as were air concentration of particle number and particle surface area of fine particles. The personal exposure levels of inhalable dust were consistently low (AM 0.15mg m−3, range industrial settings. Regression analysis implied the use of stationary determined mass-based and particle surface area aerosol concentration as proxies for various exposure measures in our study. PMID:27143598

  17. Errors analysis in the evaluation of particle concentration by PDA on a turbulent two-phase jet: application for cross section and transit time methods

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, Esteban; Garcia, Juan A.; Garcia, Ignacio; Aisa, Luis A. [University of Zaragoza, Area de Mecanica de Fluidos, Centro Politecnico Superior, Zaragoza (Spain)

    2009-09-15

    Phase-Doppler anemometry (PDA) is a powerful tool for two-phase flow measurements and testing. Particle concentration and mass flux can also be evaluated using the raw particle data supplied by this technique. The calculation starts from each particle velocity, diameter, transit time data, and the total measurement time. There are two main evaluation strategies. The first one uses the probe volume effective cross section, and it is usually simplified assuming that particles follow quasi one-directional trajectories. In the text, it will be called the cross section method. The second one includes a set of methods which will be denoted as ''Generalized Integral Methods'' (GIM). Concentration algorithms such as the transit time method (TTM) and the integral volume method (IVM) are particular cases of the GIM. In any case, a previous calibration of the measurement volume geometry is necessary to apply the referred concentration evaluation methods. In this study, concentrations and mass fluxes both evaluated by the cross-section method and the TTM are compared. Experimental data are obtained from a particle-laden jet generated by a convergent nozzle. Errors due to trajectory dispersion, burst splitting, and multi-particle signals are discussed. (orig.)

  18. Concentrations and abundance ratios of long-chain alkenones and glycerol dialkyl glycerol tetraethers in sinking particles south of Java

    Science.gov (United States)

    Chen, Wenwen; Mohtadi, Mahyar; Schefuß, Enno; Mollenhauer, Gesine

    2016-06-01

    In this study, we obtained concentrations and abundance ratios of long-chain alkenones and glycerol dialkyl glycerol tetraethers (GDGTs) in a one-year time-series of sinking particles collected with a sediment trap moored from December 2001 to November 2002 at 2200 m water depth south of Java in the eastern Indian Ocean. We investigate the seasonality of alkenone and GDGT fluxes as well as the potential habitat depth of the Thaumarchaeota producing the GDGTs entrained in sinking particles. The alkenone flux shows a pronounced seasonality and ranges from 1 μg m-2 d-1 to 35 μg m-2 d-1. The highest alkenone flux is observed in late September during the Southeast monsoon, coincident with high total organic carbon fluxes as well as high net primary productivity. Flux-weighted mean temperature for the high flux period using the alkenone-based sea-surface temperature (SST) index U37K‧ is 26.7 °C, which is similar to satellite-derived Southeast (SE) monsoon SST (26.4 °C). The GDGT flux displays a weaker seasonality than that of the alkenones. It is elevated during the SE monsoon period compared to the Northwest (NW) monsoon and intermonsoon periods (approximately 2.5 times), which is probably related to seasonal variation of the abundance of Thaumarchaeota, or to enhanced export of GDGTs by aggregation with sinking phytoplankton detritus. Flux-weighted mean temperature inferred from the GDGT-based TEX86H index is 26.2 °C, which is 1.8 °C lower than mean annual (ma) SST but similar to SE monsoon SST. As the time series of TEX86H temperature estimates, however, does not record a strong seasonal amplitude, we infer that TEX86H reflects ma upper thermocline temperature at approximately 50 m water depth.

  19. Monitoring of black carbon and size-segregated particle number concentrations at 9-m and 65-m distances from a major road in Helsinki

    Energy Technology Data Exchange (ETDEWEB)

    Pakkanen, T.A.; Maekelae, T.; Hillamo, R.E. [Finnish Meteorological Inst., Helsinki (Finland); Virtanen, A.; Roenkkoe, T.; Keskinen, J. [Tampere Univ. of Technology, Inst. of Physics, Aerosol Physics Lab. , Tampere (Finland); Pirjola, L.; Parviainen, H. [Helsinki Polytechnic, Dept. of Technology, Helsinki (Finland); Hussein, T.; Haemeri, K. [Helsinki Univ., Dept. of Physical Sciences, Helsinki (Finland)

    2006-07-01

    In February and August 2003, black carbon (BC) and size-segregated particle number concentrations were monitored simultaneously at 9-m and 65-m distances from a major road in Helsinki, Finland, using aethalometers and electrical low-pressure impactors, respectively. During weekdays in winter, the average total particle number concentrations in the diameter range 0.007-1{mu}m increased during morning rush hours from the nighttime values of 17000 and 12000 cm{sup -3} to 190000 and 130000 cm{sup -3} at the 9-m and 65-m stations, respectively. The corresponding BC concentrations increased from 730 and 430 ng m{sup -3} to 2800 and 1550 ng m{sup -3}. Compared with those in winter, the average rush-hour particle number concentrations were much lower in summer, the likely reason being enhanced nucleation in cold winter conditions. BC concentrations were slightly higher during summer than during winter. Number size distributions measured at the 9-m and 65-m distances and at a background site had similar modal characteristics with the highest peak occurring below 0.03 {mu}m. Despite the different wind conditions in winter and summer, concentrations of total particle number and BC decreased similarly between the 9-m and 65-m stations, the likely principal mechanism being mixing with background air. The strong diurnal variation in concentrations during the weekdays, together with the large concentration difference between the 9-m and 65-m distances, suggests that local traffic was the main source of the measured pollutants, especially during rush hours at the 9-m site. In winter, the decrease in the particle number concentrations from the 9-m site to the 65-m site was most pronounced for the smallest exhaust particles. During an episodic pollution event in winter there were indications of condensational growth of 0.007-0.03 {mu}m particles, which increased the number concentration of 0.03-0.06 {mu}m particles at the 65-m site. (orig.)

  20. Concentrations and solubility of trace elements in fine particles at a mountain site, southern China: regional sources and cloud processing

    Science.gov (United States)

    Li, T.; Wang, Y.; Li, W. J.; Chen, J. M.; Wang, T.; Wang, W. X.

    2015-08-01

    The concentrations and solubility of twelve trace elements in PM2.5 at Mt. Lushan, southern China, were investigated during the summer of 2011 and the spring of 2012. The average PM2.5 mass was 55.2 ± 20.1 μg m-3 during the observation period. Temporal variations of all trace elements including total and water-soluble fractions with several dust storm spikes in total fractions of Al and Fe were observed. The enrichment factor (EF) values were 1 order of magnitude higher for the water-soluble fractions versus the total fractions of trace elements. Four major emission sources, namely nonferrous metal mining and smelting (for Cr, As, Ba and parts of Zn), coal combustion (for Pb, Zn, Se, Cu and Mn), crustal materials (for Al and Fe) and municipal solid waste incineration (for Cd and Mo), were classified by principal component analysis (PCA). Trajectory cluster analysis and the potential source contribution function (PSCF) consistently identified the Yangtze River delta (YRD), the Pearl River delta (PRD), and the neighbouring provinces of Mt. Lushan as the major source regions and transport pathways for anthropogenic elements. Northern China was identified as a major source region for crustal elements. It should be noted that apart from the YRD, the area around Mt. Lushan has become the most significant contributor to the solubility of most trace elements. Element solubility can be partially determined by emission sources. However, enhanced solubility of trace elements corresponding to increased concentrations of sulfate after the occurrence of cloud events indicated significant effects of cloud processing on aerosol element dissolution. Metal particles mixed with sulfate in cloud droplet residues were further investigated through transmission electron microscopy (TEM) analysis. Irreversible alteration of particle morphology by cloud processing was confirmed to be highly responsible for the enhancement of trace element solubility. The findings from this study imply an

  1. Concentration device

    DEFF Research Database (Denmark)

    2013-01-01

    A concentration device (2) for filter filtration concentration of particles (4) from a volume of a fluid (6). The concentration device (2) comprises a filter (8) configured to filter particles (4) of a predefined size in the volume of the fluid (6). The concentration device (2) comprises...

  2. Hepatitis C virus G1b infection decreases the number of small low-density lipoprotein particles.

    Science.gov (United States)

    Kinoshita, Chika; Nagano, Tomohisa; Seki, Nobuyoshi; Tomita, Yoichi; Sugita, Tomonori; Aida, Yuta; Itagaki, Munenori; Satoh, Kenichi; Sutoh, Satoshi; Abe, Hiroshi; Tsubota, Akihito; Aizawa, Yoshio

    2016-08-07

    To investigate how hepatitis C virus (HCV) G1b infection influences the particle number of lipoproteins. The numbers of lipoprotein particles in fasting sera from 173 Japanese subjects, 82 with active HCV G1b infection (active HCV group) and 91 with cleared HCV infection (SVR group), were examined. Serum lipoprotein was fractionated by high-performance liquid chromatography into twenty fractions. The cholesterol and triglyceride concentrations in each fraction were measured using LipoSEARCH. The number of lipoprotein particles in each fraction was calculated using a newly developed algorithm, and the relationship between chronic HCV G1b infection and the lipoprotein particle number was determined by multiple linear regression analysis. The median number of low-density lipoprotein (LDL) particles was significantly lower in the active HCV group [1182 nmol/L, interquartile range (IQR): 444 nmol/L] than in the SVR group (1363 nmol/L, IQR: 472 nmol/L, P lipoprotein (HDL) particles (14168 nmol/L vs 15054 nmol/L, IQR: 4114 nmol/L vs 3385 nmol/L, P = 0.042). The number of very low-density lipoprotein (VLDL) particles was similar between the two groups. Among the four LDL sub-fractions, the number of large LDL particles was similar between the two groups. However, the numbers of medium (median: 533.0 nmol/L, IQR: 214.7 nmol/L vs median: 633.5 nmol/L, IQR: 229.6 nmol/L, P < 0.001), small (median: 190.9 nmol/L, IQR: 152.4 nmol/L vs median: 263.2 nmol/L, IQR: 159.9 nmol/L; P < 0.001), and very small LDL particles (median: 103.5 nmol/L, IQR: 66.8 nmol/L vs median: 139.3 nmol/L, IQR: 67.3 nmol/L, P < 0.001) were significantly lower in the active HCV group than in the SVR group, respectively. Multiple linear regression analysis indicated an association between HCV G1b infection and the decreased numbers of medium, small, and very small LDL particles. However, active HCV infection did not affect the number of large LDL particles or any sub-fractions of VLDL and HDL particles. HCV

  3. Kinetic and Related Determinants of Plasma Triglyceride Concentration in Abdominal Obesity: Multicenter Tracer Kinetic Study.

    Science.gov (United States)

    Borén, Jan; Watts, Gerald F; Adiels, Martin; Söderlund, Sanni; Chan, Dick C; Hakkarainen, Antti; Lundbom, Nina; Matikainen, Niina; Kahri, Juhani; Vergès, Bruno; Barrett, P Hugh R; Taskinen, Marja-Riitta

    2015-10-01

    Patients with obesity and diabetes mellitus have increased risk of cardiovascular disease. A major cause is an atherogenic dyslipidemia related primarily to elevated plasma concentrations of triglyceride-rich lipoproteins. The aim of this study was to clarify determinants of plasma triglyceride concentration. We focused on factors that predict the kinetics of very-low density lipoprotein 1 (VLDL1) triglycerides. A multicenter study using dual stable isotopes (deuterated leucine and glycerol) and multicompartmental modeling was performed to elucidate the kinetics of triglycerides and apoB in VLDL1 in 46 subjects with abdominal obesity and additional cardiometabolic risk factors. Results showed that plasma triglyceride concentrations were dependent on both the secretion rate (r=0.44, Ptriglycerides and VLDL1-apoB. Liver fat mass was independently and directly associated with secretion rates of VLDL1-triglycerides (r=0.56, Ptriglycerides (r=0.48, Ptriglyceride concentrations in abdominal obesity are determined by the kinetics of VLDL1 subspecies, catabolism being mainly dependent on apoC-III concentration and secretion on liver fat content. Reduction in liver fat and targeting apoC-III may be an effective approach for correcting triglyceride metabolism atherogenic dyslipidemia in obesity. © 2015 American Heart Association, Inc.

  4. Evaluation and modeling of the size fractionated aerosol particle number concentration measurements nearby a major road in Helsinki ─ Part II: Aerosol measurements within the SAPPHIRE project

    Directory of Open Access Journals (Sweden)

    A. Karppinen

    2007-08-01

    Full Text Available This study presents an evaluation and modeling exercise of the size fractionated aerosol particle number concentrations measured nearby a major road in Helsinki during 23 August–19 September 2003 and 14 January–11 February 2004. The available information also included electronic traffic counts, on-site meteorological measurements, and urban background particle number size distribution measurement. The ultrafine particle (UFP, diameter<100 nm number concentrations at the roadside site were approximately an order of magnitude higher than those at the urban background site during daytime and downwind conditions. Both the modal structure analysis of the particle number size distributions and the statistical correlation between the traffic density and the UFP number concentrations indicate that the UFP were evidently from traffic related emissions. The modeling exercise included the evolution of the particle number size distribution nearby the road during downwind conditions. The model simulation results revealed that the evaluation of the emission factors of aerosol particles might not be valid for the same site during different time.

  5. Fluorescent biological aerosol particle concentrations and size distributions measured with an ultraviolet aerodynamic particle sizer (UV-APS) in Central Europe

    OpenAIRE

    J. A. Huffman; Treutlein, B.; U. Pöschl

    2009-01-01

    Primary Biological Aerosol Particles (PBAPs), including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany we used an Ultraviolet Aerodynamic Particle Sizer (UV-APS) to measure ...

  6. Contribution of new particle formation to the total aerosol concentration at the high-altitude site Jungfraujoch (3580 m asl, Switzerland)

    Science.gov (United States)

    Tröstl, Jasmin; Herrmann, Erik; Frege, Carla; Bianchi, Federico; Molteni, Ugo; Bukowiecki, Nicolas; Hoyle, Christopher R.; Steinbacher, Martin; Weingartner, Ernest; Dommen, Josef; Gysel, Martin; Baltensperger, Urs

    2016-10-01

    Previous modeling studies hypothesized that a large fraction of cloud condensation nuclei (CCN) is attributed to new particle formation (NPF) in the free troposphere. Despite the potential importance of this process, only few long-term observations have been performed to date. Here we present the results of a 12 month campaign of NPF observations at the high-altitude site Jungfraujoch (JFJ, 3580 m above sea level (asl)). Our results show that NPF significantly adds to the total aerosol concentration at the JFJ and only occurs via previous precursor entrainment from the planetary boundary layer (PBL). Freshly nucleated particles do not directly grow to CCN size (90 nm) within observable time scales (maximum 48 h). The contribution of NPF to the CCN concentration is low within this time frame compared to other sources, such as PBL entrainment of larger particles. A multistep growth mechanism is proposed which allows previously formed Aitken mode particles to add to the CCN concentration. A parametrization is derived to explain formation rates at the JFJ, showing that precursor concentration, PBL influence, and global radiation are the key factors controlling new particle formation at the site.

  7. Dispensing of high concentration Ag nano-particles ink for ultra-low resistivity paper-based writing electronics.

    Science.gov (United States)

    Wang, Fuliang; Mao, Peng; He, Hu

    2016-02-17

    Paper-based writing electronics has received a lot of interest recently due to its potential applications in flexible electronics. To obtain ultra-low resistivity paper-based writing electronics, we developed a kind of ink with high concentration of Ag Nano-particles (up to 80 wt%), as well as a related dispensing writing system consisting an air compressor machine and a dispenser. Additionally, we also demonstrated the writability and practical application of our proposed ink and writing system. Based on the study on the effect of sintering time and pressure, we found the optimal sintering time and pressure to obtain high quality Ag NPs wires. The electrical conductivity of nano-silver paper-based electronics has been tested using the calculated resistivity. After hot-pressure sintering at 120 °C, 25 MPa pressure for 20 minutes, the resistivity of silver NPs conductive tracks was 3.92 × 10(-8) (Ωm), only 2.45 times of bulk silver. The mechanical flexibility of nano-silver paper-based electronics also has been tested. After 1000 bending cycles, the resistivity slightly increased from the initial 4.01 × 10(-8) to 5.08 × 10(-8) (Ωm). With this proposed ink preparation and writing system, a kind of paper-based writing electronics with ultra-low resistivity and good mechanical flexibility was achieved.

  8. Particle number concentration near road traffic in Amsterdam (the Netherlands): Comparison of standard and real-world emission factors

    Science.gov (United States)

    Keuken, M. P.; Moerman, M.; Voogt, M.; Zandveld, P.; Verhagen, H.; Stelwagen, U.; Jonge de, D.

    2016-05-01

    In this study, NOx and particle number concentration (PNC) at an urban background and a traffic location were measured in the city of Amsterdam (the Netherlands). Modelled and measured contributions to NOx and PNC at the traffic location were used to derive real-world PN emission factors for average urban road traffic. The results for NOx were applied to validate our approach. The real-world PN emission factors (#.km-1) were 2.9E+14 (urban road) and 3E+14 (motorway). These values were at least a factor eight higher than dynamometer-based PN emission factors from COPERT 4 and HBEFA databases. The real-world PN emission factors were used to model the contribution to PNC near road traffic in 2014. This was two to three times higher than the PNC urban background along urban roads over 20,000 vehicles per day and near motorways. The discrepancy between dynamometer-based and real-world emission factors demonstrates the need for more PNC observations to assess actual PN emissions from road traffic.

  9. Concentration, origin and health hazard from fine particle-bound PAH at three characteristic sites in Southern Poland.

    Science.gov (United States)

    Rogula-Kozłowska, Wioletta; Kozielska, Barbara; Klejnowski, Krzysztof

    2013-09-01

    Suspended particles with the aerodynamic diameters not greater than 2.5 μm (PM2.5) and 1 μm (PM1, sub-fraction of PM2.5) were sampled at three sites: an urban background site, rural background site, and urban traffic site in southern Poland. In total, there were 240 samples taken within 02.08.2009-27.12.2010. Fifteen polycyclic aromatic hydrocarbons (PAH) were determined in each dust fraction. The averages of the concentration of total PAH (ΣPAH) and of particular PAH, as well as the share of carcinogenic PAH in total PAH (ΣPAHcarc/ΣPAH), carcinogenic equivalent, mutagenic equivalent, and TCDD-toxic equivalent appeared high compared to other areas in the world. Their high values express the significance of health hazard from PM and PM-bound PAH in southern Poland. The diagnostic ratios suggest that PM-bound PAH originate from municipal (PM1-2.5) and vehicular (PM1) combustion.

  10. Determining the concentration of procalcitonin using a magnetic particles-based chemiluminescence assay for the clinical diagnosis of sepsis.

    Science.gov (United States)

    Qi, Suwen; Li, Qiaoliang; Rao, Wei; Liu, Xinyu; Yin, Li; Zhang, Huisheng

    2013-01-01

    Our objective is to develop an assay based on magnetic particles (MPs) to determine the concentration of procalcitonin (PCT) using a chemiluminescence immunoassay (CLIA). Fluorescein isothiocyanate (FITC) and N-(aminobutyl)-N-(ethylisoluminol) (ABEI) were used to label two different anti-procalcitonin (PCT) monoclonal antibodies. The labeled antibodies, the PCT antigen, and the anti-FITC antibody-coated MPs formed a double-sandwiched immunocomplex. The measured relative light units (RLUs) of ABEI in the substrate solution were directly proportional to the amount of PCT present in the samples. The proposed method was linear to 600 ng/mL with a detection limit of 0.03 ng/mL. The coefficient of variation (CV) was <5% and <6% for the intra- and inter-assay precision, respectively. The average recoveries were between 95 and 107%. The linearity-dilution effect gave a linear correlation coefficient of 0.9912. This proposed assay provided an alternative method to quantitatively measure PCT in serum for the diagnosis of sepsis.

  11. Effect of Cr(VI) concentration on gas and particle production during iron oxidation in aqueous solutions containing Cl(-) ions.

    Science.gov (United States)

    Ahn, Hyangsig; Jo, Ho Young; Ryu, Ji-Hun; Koh, Yong-Kwon

    2017-02-01

    Zero-valent iron (ZVI) is commonly used as a medium in permeable reactive barriers (PRBs) because of its high reducing ability. The generation of H2 gas in PRBs, however, can decrease the permeability of PRBs and reduce the contact area between the PRB and contaminated groundwater. This study investigated the effect of the initial Cr(VI) concentration ([Cr(VI)init]) in aqueous solutions containing Cl(-) ions on the generation of H2 gas. ZVI chips were reacted in reactors with 0.5-M NaCl solutions with [Cr(VI)init] ranging between 51 and 303 mg/L. The initial pH was set at 3. The oxidation of ZVI chips by Cr(VI) in aqueous solutions containing Cl(-) ions produced H2 gas and particles (Fe(III)-Cr(III)(oxy)hydroxides). The Cr(VI) removal from aqueous solutions increased as the [Cr(VI)init] increased, as did H2 gas generation. The positive effect of [Cr(VI)init] on H2 gas generation might be due to an increase in the redox potential gradient as [Cr(VI)init] increases. This increased gradient would enhance H(+) ion penetration through the passive film (Fe(III)-Cr(III)(oxy)hydroxides), which formed on the ZVI surface, by diffusion from the solution to pits beneath the passive film.

  12. Concentration and composition of dust particles in surface snow at Urumqi Glacier No. 1, Eastern Tien Shan

    Science.gov (United States)

    Wu, Guangjian; Zhang, Xuelei; Zhang, Chenglong; Gao, Shaopeng; Li, Zhongqin; Wang, Feiteng; Wang, Wenbin

    2010-10-01

    Major, trace, and rare earth elements (REE) were determined by inductively coupled plasma-mass spectrometer (ICP-MS) for dust particles that were extracted from fresh surface snow samples collected weekly or biweekly between March 2006 and January 2008 at Urumqi Glacier No. 1 (UG1) in Eastern Tien Shan, Central Asia. The UG1 dust shows average Fe/Al ratios of 0.7, Ca/Al ratios of 0.35, La/Th ratios of 2.62, Th/U ratios of 3.31, an Eu anomaly of 0.63, and L/HREE ratios of 7.87. Seasonal variation is significant in dust concentration, but is not observed in dust composition, which remains rather uniform throughout the sampling period. The compositional homogeneity suggests that dust materials in UG1 are well mixed from their possible source areas. Fine materials from the Junggar Basin, and to a less extend from Tarim Basin, more closely resemble UG1 dust properties in their REE composition than do the local moraines, indicating that the dust in UG1 snow mainly comes from mid- to long-range source areas. The HYSPLIT model results suggest that the Westerlies, Arctic air masses and local winds are the main circulations for dust transport to Eastern Tien Shan.

  13. Comparison of a reduced carbohydrate and reduced fat diet for LDL, HDL, and VLDL subclasses during 9-months of weight maintenance subsequent to weight loss

    Directory of Open Access Journals (Sweden)

    Vernon Mary C

    2010-06-01

    Full Text Available Abstract Objectives This study compared LDL, HDL, and VLDL subclasses in overweight or obese adults consuming either a reduced carbohydrate (RC or reduced fat (RF weight maintenance diet for 9 months following significant weight loss. Methods Thirty-five (21 RC; 14 RF overweight or obese middle-aged adults completed a 1-year weight management clinic. Participants met weekly for the first six months and bi-weekly thereafter. Meetings included instruction for diet, physical activity, and behavior change related to weight management. Additionally, participants followed a liquid very low-energy diet of ~2092 kJ per day for the first three months of the study. Subsequently, participants followed a dietary plan for nine months that targeted a reduced percentage of carbohydrate (~20% or fat (~30% intake and an energy intake level calculated to maintain weight loss. Lipid subclasses using NMR spectroscopy were analyzed prior to weight loss and at multiple intervals during weight maintenance. Results Body weight change was not significantly different within or between groups during weight maintenance (p > 0.05. The RC group showed significant increases in mean LDL size, large LDL, total HDL, large and small HDL, mean VLDL size, and large VLDL during weight maintenance while the RF group showed increases in total HDL, large and small HDL, total VLDL, and large, medium, and small VLDL (p p > 0.05. Conclusion Some individual lipid subclasses improved in both dietary groups. Large and medium VLDL subclasses increased to a greater extent across weight maintenance in the RF group.

  14. A quasi-stationary approach to particle concentration and distribution in gear oil for wear mode estimation

    DEFF Research Database (Denmark)

    Henneberg, Morten; Eriksen, René Lynge; Jørgensen, Bent

    2015-01-01

    Suspension of wear particles in gear oil with respect to the diversity of particle size combined with filter mechanisms has been analyzed. Coupling of wear modes from tribology is combined with particle size bins to show how a mathematical model can be expanded to include information gained from...... sensors that can segment particles into size bins. In order to establish boundary conditions for the model based on real data, a filtration test is included. Finally, the model is fitted to data from a gear in operation and differences between real data and the model are discussed. The findings show...... that particles less than 14 μm dominate the wear. Hence, it is concluded that abrasion dominate the wear, for the gear in operation, and it is concluded to be in quasi-stationary mode. The distribution of the particles is observed in conjunction with the particle quantity to determine a basis for normal...

  15. A high gradient and strength bioseparator with nano-sized immunomagnetic particles for specific separation and efficient concentration of E. coli O157:H7

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jianhan, E-mail: jianhan@cau.edu.cn [Ministry of Agriculture Key Laboratory of Agricultural Information Acquisition Technology (Beijing), 17 East Tsinghua Road, China Agricultural University, Mailbox 125, Beijing 100083 (China); Li, Min [College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058 (China); Li, Yanbin [College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058 (China); Department of Biological and Agricultural Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Chen, Qi [Modern Precision Agriculture System Integration Research Key Laboratory of Ministry of Education, China Agricultural University, Beijing 100083 (China)

    2015-03-15

    Sample pretreatment is a key to rapid screening of pathogens for prevention and control of foodborne diseases. Magnetic immunoseparation is a specific method based on antibody–antigen reaction to capture the target bacteria and concentrate them in a smaller-volume buffer. The use of nano-sized magnetic particles could improve the separation efficiency of bacteria but require much higher gradient and strength magnetic field. In this study, a strong magnetic bioseparator with a mean field strength of 1.35 T and a mean gradient of 90 T/m was developed with the use of the 30 nm and 180 nm magnetic particles to specifically separate and efficiently concentrate foodborne bacterial pathogens using Escherichia coli O157:H7 as a model bacterium. The polyclonal antibodies against E. coli were evaluated using Dot ELISA analysis for their good affinity with the target bacteria and then used to modify the surface of the magnetic nanoparticles by 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) method and streptavidin-biotin binding. The magnetic particle concentrations were optimized to be 40 µg/ml and 100 µg/ml for the 30 nm and 180 nm particles, respectively, the immunoreaction time was optimized to be 45 min for both sizes of particles, and the separation times were optimized to be 60 min and 2 min for the 30 nm and 180 nm particles, respectively. The total magnetic separation time was 2 h and 1 h for the 30 nm and 180 nm particles, respectively. The experimental results demonstrated that the bioseparator with the use of either 30 nm or 180 nm immunomagnetic particles could achieve a separation efficiency of >90% for E. coli O157:H7 at the concentrations ranging from 10{sup 2} to 10{sup 5} cfu/ml. No obvious interferences from non-target foodborne pathogens, such as SalmonellaTyphimurium and Listeria innocua, were found. For overall consideration of the consuming time, the cost, and the separation efficiency, the 180 nm magnetic particles are

  16. An Integrated Instrumentation System for Velocity, Concentration and Mass Flow Rate Measurement of Solid Particles Based on Electrostatic and Capacitance Sensors.

    Science.gov (United States)

    Li, Jian; Kong, Ming; Xu, Chuanlong; Wang, Shimin; Fan, Ying

    2015-12-10

    The online and continuous measurement of velocity, concentration and mass flow rate of pneumatically conveyed solid particles for the high-efficiency utilization of energy and raw materials has become increasingly significant. In this paper, an integrated instrumentation system for the velocity, concentration and mass flow rate measurement of dense phase pneumatically conveyed solid particles based on electrostatic and capacitance sensorsis developed. The electrostatic sensors are used for particle mean velocity measurement in combination with the cross-correlation technique, while the capacitance sensor with helical surface-plate electrodes, which has relatively homogeneous sensitivity distribution, is employed for the measurement of particle concentration and its capacitance is measured by an electrostatic-immune AC-based circuit. The solid mass flow rate can be further calculated from the measured velocity and concentration. The developed instrumentation system for velocity and concentration measurement is verified and calibrated on a pulley rig and through static experiments, respectively. Finally the system is evaluated with glass beads on a gravity-fed rig. The experimental results demonstrate that the system is capable of the accurate solid mass flow rate measurement, and the relative error is within -3%-8% for glass bead mass flow rates ranging from 0.13 kg/s to 0.9 kg/s.

  17. An Integrated Instrumentation System for Velocity, Concentration and Mass Flow Rate Measurement of Solid Particles Based on Electrostatic and Capacitance Sensors

    Directory of Open Access Journals (Sweden)

    Jian Li

    2015-12-01

    Full Text Available The online and continuous measurement of velocity, concentration and mass flow rate of pneumatically conveyed solid particles for the high-efficiency utilization of energy and raw materials has become increasingly significant. In this paper, an integrated instrumentation system for the velocity, concentration and mass flow rate measurement of dense phase pneumatically conveyed solid particles based on electrostatic and capacitance sensorsis developed. The electrostatic sensors are used for particle mean velocity measurement in combination with the cross-correlation technique, while the capacitance sensor with helical surface-plate electrodes, which has relatively homogeneous sensitivity distribution, is employed for the measurement of particle concentration and its capacitance is measured by an electrostatic-immune AC-based circuit. The solid mass flow rate can be further calculated from the measured velocity and concentration. The developed instrumentation system for velocity and concentration measurement is verified and calibrated on a pulley rig and through static experiments, respectively. Finally the system is evaluated with glass beads on a gravity-fed rig. The experimental results demonstrate that the system is capable of the accurate solid mass flow rate measurement, and the relative error is within −3%–8% for glass bead mass flow rates ranging from 0.13 kg/s to 0.9 kg/s.

  18. Observations of particle extinction, PM2.5 mass concentration profile and flux in north China based on mobile lidar technique

    Science.gov (United States)

    Lv, Lihui; Liu, Wenqing; Zhang, Tianshu; Chen, Zhenyi; Dong, Yunsheng; Fan, Guangqiang; Xiang, Yan; Yao, Yawei; Yang, Nan; Chu, Baolin; Teng, Man; Shu, Xiaowen

    2017-09-01

    Fine particle with diameter limited by the lack of monitoring data obtained with multiple fixed site sampling strategies. Mobile monitoring has provided a means for broad measurement of fine particles. In this research, the potential use of mobile lidar to map the distribution and transport of fine particles was discussed. The spatial and temporal distributions of particle extinction, PM2.5 mass concentration and regional transport flux of fine particle in the planetary boundary layer were investigated with the use of vehicle-based mobile lidar and wind field data from north China. Case studies under different pollution levels in Beijing were presented to evaluate the contribution of regional transport. A vehicle-based mobile lidar system was used to obtain the spatial and temporal distributions of particle extinction in the measurement route. Fixed point lidar and a particulate matter sampler were operated next to each other at the University of Chinese Academy of Science (UCAS) in Beijing to determine the relationship between the particle extinction coefficient and PM2.5 mass concentration. The correlation coefficient (R2) between the particle extinction coefficient and PM2.5 mass concentration was found to be over 0.8 when relative humidity (RH) was less than 90%. A mesoscale meteorological model, the Weather Research and Forecasting (WRF) model, was used to obtain profiles of the horizontal wind speed, wind direction and relative humidity. A vehicle-based mobile lidar technique was applied to estimate transport flux based on the PM2.5 profile and vertical profile of wind data. This method was applicable when hygroscopic growth can be neglected (relatively humidity<90%). Southwest was found to be the main pathway of Beijing during the experiments.

  19. Source apportionment of fine PM and sub-micron particle number concentrations at a regional background site in the western Mediterranean: a 2.5 yr study

    Science.gov (United States)

    Cusack, M.; Pérez, N.; Pey, J.; Alastuey, A.; Querol, X.

    2013-02-01

    The chemical composition and sources of ambient fine particulate matter (PM1) over a period of 2.5 yr for a regional background site in the western Mediterranean are presented in this work. Major components (such as SO12-, NO3-, NH4+, organic and elemental carbon) and trace elements were analysed and the emission sources affecting PM1 were determined using Positive Matrix Factorisation (PMF). Furthermore, sub-micron particle number concentrations and the sources of these particles are also presented. Sources of sub-micron particles were determined by Principal Component Analysis (PCA). The mean PM1 concentration for the measurement period was 8.9 μg m-3, with organic matter (OM) and sulphate comprising most of the mass (3.2 and 1.5 μg m-3). A clear seasonal variation was recorded with higher PM1 concentrations in summer (11.2 μg m-3) compared to winter (6.6 μg m-3). This summer increase was due to elevated levels of sulphate and OM. Six sources were identified by PMF: secondary organic aerosol, secondary nitrate, industrial, traffic + biomass burning, fuel oil combustion and secondary sulphate. The daily variations of these sources were also determined, whereby the typically anthropogenic sources displayed elevated concentrations during the week with reductions at weekends. Nitrate levels were elevated in winter and negligible in summer, whereas secondary sulphate levels underwent a contrasting seasonal evolution with highest concentrations in summer, similar to the fuel oil combustion source. The SOA source was influenced by episodes of sustained pollution as a result of anticyclonic conditions occurring during winter, giving rise to thermal inversions and the accumulation of pollutants in the mixing layer. Increased levels in summer were owing to higher biogenic emissions and regional recirculation of air masses. The industrial source decreased in August due to decreased emissions during the vacation period. Increases in the traffic + biomass burning source

  20. Observations of urban airborne particle number concentrations during rush-hour conditions: analysis of the number based size distributions and modal parameters.

    Science.gov (United States)

    Lingard, Justin J N; Agus, Emily L; Young, David T; Andrews, Gordon E; Tomlin, Alison S

    2006-12-01

    A summertime study of the number concentration and the size distribution of combustion derived nanometre sized particles (termed nanoparticles) from diesel and spark-ignition (SI) engine emissions were made under rush-hour and free-flow traffic conditions at an urban roadside location in Leeds, UK in July 2003. The measured total particle number concentrations (N(TOTAL)) were of the order 1.8 x 10(4) to 3.4 x 10(4) cm(-3), and tended to follow the diurnal traffic flow patterns. The N(TOTAL) was dominated by particles particle number. By use of a log-normal fitting procedure, the modal parameters of the number based particle size distribution of urban airborne particulates were derived from the roadside measurements. Four component modes were identified. Two nucleation modes were found, with a smaller, more minor, mode composed principally of sub-11 nm particles, believed to be derived from particles formed from the nucleation of gaseous species in the atmosphere. A second mode, much larger in terms of number, was composed of particles within the size range of 10-20 nm. This second mode was believed to be principally derived from the condensation of the unburned fuel and lube oil (the solvent organic fraction or SOF) as it cooled on leaving the engine exhaust. Third and fourth modes were noted within the size ranges of 28-65 nm and 100-160 nm, respectively. The third mode was believed to be representative of internally mixed Aitken mode particles composed of a soot/ash core with an adsorbed layer of readily volatilisable material. The fourth mode was believed to be composed of chemically aged, secondary particles. The larger nucleation and Aitken modes accounted for between 80-90% of the measured N(TOTAL), and the particles in these modes were believed to be derived from SI and diesel engine emissions. The overall size distribution, particularly in modes II-IV, was observed to be strongly related to the number of primary particle emissions, with larger count median

  1. Final Technical Report: Using Solid Particles as Heat Transfer Fluid for use in Concentrating Solar Power (CSP) Plants

    Energy Technology Data Exchange (ETDEWEB)

    Lattanzi, Aaron [Univ. of Colorado, Boulder, CO (United States); Hrenya, Christine [Univ. of Colorado, Boulder, CO (United States)

    2016-03-31

    In today’s industrial economy, energy consumption has never been higher. Over the last 15 years the US alone has consumed an average of nearly 100 quadrillion BTUs per year [21]. A need for clean and renewable energy sources has become quite apparent. The SunShot Initiative is an ambitious effort taken on by the United States Department of Energy that targets the development of solar energy that is cost-competitive with other methods for generating electricity. Specifically, this work is concerned with the development of concentrating solar power plants (CSPs) with granular media as the heat transfer fluid (HTF) from the solar receiver. Unfortunately, the prediction of heat transfer in multiphase flows is not well understood. For this reason, our aim is to fundamentally advance the understanding of multiphase heat transfer, particularly in gas-solid flows, while providing quantitative input for the design of a near black body receiver (NBB) that uses solid grains (like sand) as the HTF. Over the course of this three-year project, a wide variety of contributions have been made to advance the state-of-the art description for non-radiative heat transfer in dense, gas-solid systems. Comparisons between a state-of-the-art continuum heat transfer model and discrete element method (DEM) simulations have been drawn. The results of these comparisons brought to light the limitations of the continuum model due to inherent assumptions in its derivation. A new continuum model was then developed for heat transfer at a solid boundary by rigorously accounting for the most dominant non-radiative heat transfer mechanism (particle-fluid-wall conduction). The new model is shown to be in excellent agreement with DEM data and captures the dependence of heat transfer on particle size, a dependency that previous continuum models were not capable of. DEM and the new continuum model were then employed to model heat transfer in a variety of receiver geometries. The results provided crucial

  2. Characterization of metabolic interrelationships and in silico phenotyping of lipoprotein particles using self-organizing maps[S

    Science.gov (United States)

    Kumpula, Linda S.; Mäkelä, Sanna M.; Mäkinen, Ville-Petteri; Karjalainen, Anna; Liinamaa, Johanna M.; Kaski, Kimmo; Savolainen, Markku J.; Hannuksela, Minna L.; Ala-Korpela, Mika

    2010-01-01

    Plasma lipid concentrations cannot properly account for the complex interactions prevailing in lipoprotein (patho)physiology. Sequential ultracentrifugation (UCF) is the gold standard for physical lipoprotein isolations allowing for subsequent analyses of the molecular composition of the particles. Due to labor and cost issues, however, the UCF-based isolations are usually done only for VLDL, LDL, and HDL fractions; sometimes with the addition of intermediate density lipoprotein (IDL) particles and the fractionation of HDL into HDL2 and HDL3 (as done here; n = 302). We demonstrate via these data, with the lipoprotein lipid concentration and composition information combined, that the self-organizing map (SOM) analysis reveals a novel data-driven in silico phenotyping of lipoprotein metabolism beyond the experimentally available classifications. The SOM-based findings are biologically consistent with several well-known metabolic characteristics and also explain some apparent contradictions. The novelty is the inherent emergence of complex lipoprotein associations; e.g., the metabolic subgrouping of the associations between plasma LDL cholesterol concentrations and the structural subtypes of LDL particles. Importantly, lipoprotein concentrations cannot pinpoint lipoprotein phenotypes. It would generally be beneficial to computationally enhance the UCF-based lipoprotein data as illustrated here. Particularly, the compositional variations within the lipoprotein particles appear to be a fundamental issue with metabolic and clinical corollaries. PMID:19734566

  3. A comparison of particle-tracking and solute transport methods for simulation of tritium concentrations and groundwater transit times in river water

    Science.gov (United States)

    Gusyev, M. A.; Abrams, D.; Toews, M. W.; Morgenstern, U.; Stewart, M. K.

    2014-08-01

    The purpose of this study is to simulate tritium concentrations and groundwater transit times in river water with particle-tracking (MODPATH) and compare them to solute transport (MT3DMS) simulations. Tritium measurements in river water are valuable for the calibration of particle-tracking and solute transport models as well as for understanding of watershed storage dynamics. In a previous study, we simulated tritium concentrations in river water of the western Lake Taupo catchment (WLTC) using a MODFLOW-MT3DMS model (Gusyev et al., 2013). The model was calibrated to measured tritium in river water at baseflows of the Waihaha, Whanganui, Whareroa, Kuratau, and Omori river catchments of the WLTC. Following from that work we now utilized the same MODFLOW model for the WLTC to calculate the pathways of groundwater particles (and their corresponding tritium concentrations) using steady-state particle tracking MODPATH model. In order to simulate baseflow tritium concentrations with MODPATH, transit time distributions (TTDs) are necessary to understand the lag time between the entry and discharge points of a tracer and are generated for the river networks of the five WLTC outflows. TTDs are used in the convolution integral with an input tritium concentration time series obtained from the precipitation measurements. The resulting MODPATH tritium concentrations yield a very good match to measured tritium concentrations and are similar to the MT3DMS-simulated tritium concentrations, with the greatest variation occurring around the bomb peak. MODPATH and MT3DMS also yield similar mean transit times (MTTs) of groundwater contribution to river baseflows, but the actual shape of the TTDs is strikingly different. While both distributions provide valuable information, the methodologies used to derive the TTDs are fundamentally different and hence must be interpreted differently. With the current MT3DMS model settings, only the methodology used with MODPATH provides the true TTD

  4. Measured In Situ Atmospheric Ambient Aerosol Size-Distributions, Particle Concentrations, and Turbulence Data for RSA TA-6 Test Range, Redstone Arsenal, AL, April-May 2015

    Science.gov (United States)

    2015-09-01

    Concentrations, and Turbulence Data for RSA TA-6 Test Range, Redstone Arsenal , AL, April–May 2015 by Kristan Gurton, Stephanie Cunningham, and...Aerosol Size-Distributions, Particle Concentrations, and Turbulence Data for RSA TA-6 Test Range, Redstone Arsenal , AL, April–May 2015 by Kristan...Redstone Arsenal , AL Approved for public release; distribution unlimited. ii REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188

  5. A high gradient and strength bioseparator with nano-sized immunomagnetic particles for specific separation and efficient concentration of E. coli O157:H7

    Science.gov (United States)

    Lin, Jianhan; Li, Min; Li, Yanbin; Chen, Qi

    2015-03-01

    Sample pretreatment is a key to rapid screening of pathogens for prevention and control of foodborne diseases. Magnetic immunoseparation is a specific method based on antibody-antigen reaction to capture the target bacteria and concentrate them in a smaller-volume buffer. The use of nano-sized magnetic particles could improve the separation efficiency of bacteria but require much higher gradient and strength magnetic field. In this study, a strong magnetic bioseparator with a mean field strength of 1.35 T and a mean gradient of 90 T/m was developed with the use of the 30 nm and 180 nm magnetic particles to specifically separate and efficiently concentrate foodborne bacterial pathogens using Escherichia coli O157:H7 as a model bacterium. The polyclonal antibodies against E. coli were evaluated using Dot ELISA analysis for their good affinity with the target bacteria and then used to modify the surface of the magnetic nanoparticles by 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) method and streptavidin-biotin binding. The magnetic particle concentrations were optimized to be 40 μg/ml and 100 μg/ml for the 30 nm and 180 nm particles, respectively, the immunoreaction time was optimized to be 45 min for both sizes of particles, and the separation times were optimized to be 60 min and 2 min for the 30 nm and 180 nm particles, respectively. The total magnetic separation time was 2 h and 1 h for the 30 nm and 180 nm particles, respectively. The experimental results demonstrated that the bioseparator with the use of either 30 nm or 180 nm immunomagnetic particles could achieve a separation efficiency of >90% for E. coli O157:H7 at the concentrations ranging from 102 to 105 cfu/ml. No obvious interferences from non-target foodborne pathogens, such as SalmonellaTyphimurium and Listeria innocua, were found. For overall consideration of the consuming time, the cost, and the separation efficiency, the 180 nm magnetic particles are practical for rapid

  6. Effect of injection velocity and particle concentration on transport of nanoscale zero-valent iron and hydraulic conductivity in saturated porous media.

    Science.gov (United States)

    Strutz, Tessa J; Hornbruch, Götz; Dahmke, Andreas; Köber, Ralf

    2016-08-01

    Successful groundwater remediation by injecting nanoscale zero-valent iron (NZVI) particles requires efficient particle transportation and distribution in the subsurface. This study focused on the influence of injection velocity and particle concentration on the spatial NZVI particle distribution, the deposition processes and on quantifying the induced decrease in hydraulic conductivity (K) as a result of particle retention by lab tests and numerical simulations. Horizontal column tests of 2m length were performed with initial Darcy injection velocities (q0) of 0.5, 1.5, and 4.1m/h and elemental iron input concentrations (Fe(0)in) of 0.6, 10, and 17g/L. Concentrations of Fe(0) in the sand were determined by magnetic susceptibility scans, which provide detailed Fe(0) distribution profiles along the column. NZVI particles were transported farther at higher injection velocity and higher input concentrations. K decreased by one order of magnitude during injection in all experiments, with a stronger decrease after reaching Fe(0) concentrations of about 14-18g/kg(sand). To simulate the observed nanoparticle transport behavior the existing finite-element code OGS has been successfully extended and parameterized for the investigated experiments using blocking, ripening, and straining as governing deposition processes. Considering parameter relationships deduced from single simulations for each experiment (e.g. deposition rate constants as a function of flow velocity) one mean parameter set has been generated reproducing the observations in an adequate way for most cases of the investigated realistic injection conditions. An assessment of the deposition processes related to clogging effects showed that the percentage of retention due to straining and ripening increased during experimental run time resulting in an ongoing reduction of K. Clogging is mainly evoked by straining which dominates particle deposition at higher flow velocities, while blocking and ripening play a

  7. Association between traditional cholesterol parameters, lipoprotein particle concentration, novel biomarkers and carotid plaques in retired National Football League players.

    Science.gov (United States)

    Virani, Salim S; Pompeii, Lisa; Lincoln, Andrew E; Dunn, Reginald E; Tucker, Andrew M; Nambi, Vijay; Nasir, Khurram; Vogel, Robert A; Boone, Jeffrey L; Roberts, Arthur J; Ballantyne, Christie M

    2012-06-01

    We assessed whether low-density lipoprotein particle concentration (LDL-P) and high-sensitivity C-reactive protein [hs-CRP] can identify subclinical atherosclerosis better than traditional cholesterol parameters in retired National Football League (NFL) players. It is not known whether LDL-P and the biomarker hs-CRP can identify subclinical atherosclerosis better than low-density lipoprotein cholesterol (LDL-C) or non-high-density-lipoprotein cholesterol (non-HDL-C) in retired NFL players, given high prevalence of metabolic syndrome in these players. Carotid artery plaque screening was performed with traditional lipids, LDL-P, and hs-CRP in 996 retired players. Logistic regression analyses comparing highest with the lowest quartile were performed. Carotid artery plaques were seen in 41%. LDL-C (odds ratio [OR] 1.66, 95% confidence interval [CI] 1.06-2.59), non-HDL-C (OR 1.67, 95% CI 1.04-2.67), and LDL-P (OR 2.21, 95% CI 1.35-3.62) were associated with plaques in adjusted models. Among 187 retired players with metabolic syndrome, LDL-C (OR 1.40, 95% CI 0.53-3.72) was not associated with carotid plaques, whereas LDL-P (OR 3.71, 95% CI 1.16-11.84) and non-HDL-C (OR 2.63, 95% CI 0.91-7.63, p=0.07; borderline significant) were associated with carotid plaques. hs-CRP (OR 1.13, 95% CI 0.71-1.79) was not associated with carotid plaques. Carotid artery plaques were common in retired NFL players and were strongly associated with LDL-P, especially among those with metabolic syndrome. hs-CRP was not associated with carotid plaques in this cohort. Published by Elsevier Ireland Ltd.

  8. The association between HDL particle concentration and incident metabolic syndrome in the multi-ethnic Dallas Heart Study.

    Science.gov (United States)

    Mani, Preethi; Ren, Hao-Yu; Neeland, Ian J; McGuire, Darren K; Ayers, Colby R; Khera, Amit; Rohatgi, Anand

    2016-12-12

    Metabolic syndrome (MetS) increases atherosclerotic cardiovascular disease (ASCVD) risk. Low HDL cholesterol (HDL-C) is a diagnostic criterion of MetS and a major ASCVD risk factor. HDL particle concentration (HDL-P) associates with incident ASCVD independent of HDL-C, but its association with incident MetS has not been studied. We hypothesized that HDL-P would be inversely associated with incident metabolic syndrome independent of HDL-C and markers of adiposity and insulin resistance. HDL-P was measured by NMR and visceral fat by MRI in participants of the Dallas Heart Study, a probability-based population sample of adults age 30-65. Participants with prevalent MetS, DM, CVD, and any systemic illlness were excluded. Incident MetS as defined by NCEP ATPIII criteria was determined in all participants after median follow-up period of 7.0 years. Among 1120 participants without DM or MetS at baseline (57% women, 45% Black, mean age 43), 22.8% had incident MetS at follow-up. HDL-P and HDL-C were modestly correlated (r=0.54, pHDL-C ratio, and HOMA-IR, the lowest quartile of HDL-P was associated with a 2-fold increased risk of incident MetS (OR 2.1, 95%CI 1.4-3.1; p=0.0003). Low HDL-P is independently associated with incident MetS after adjustment for traditional risk factors, lipid parameters, adiposity, inflammation, and markers of insulin resistance. Further studies are warranted to validate these findings and elucidate the mechanisms underpinning this association. Copyright © 2016. Published by Elsevier Ltd.

  9. Effects of Varying Dietary Forage Particle Size in Two Concentrate Levels on Chewing Activity, Ruminal Mat Characteristics, and Passage in Dairy Cows

    NARCIS (Netherlands)

    Zebeli, Q.; Tafaj, M.; Weber, I.; Dijkstra, J.; Steingass, H.; Drochner, W.

    2007-01-01

    The objective of this study was to investigate the effects of varying dietary forage particle size on chewing activity, ruminal mat characteristics, passage, and in situ ruminal and total tract digestion in dairy cows at a low- and high-concentrate inclusion. The experiment was designed as a 4 x 4 L

  10. The challenge of measuring sulfuric acid aerosols: number concentration and size evaluation using a condensation particle counter (CPC) and an electrical low pressure impactor (ELPI+)

    NARCIS (Netherlands)

    Brachert, L.; Mertens, J.; Khakharia, P.M.; Schaber, K.

    2014-01-01

    In this study, two different methods for the measurement of the sulfuric acid aerosol which is formed in wet flue gas cleaning processes have been investigated. The condensation particle counter (UFCPC, PALAS GmbH) provides information about the number concentration. With the electrical low pressure

  11. Effect of particle concentration on the structure and tribological properties of submicron particle SiC reinforced Ni metal matrix composite (MMC) coatings produced by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Guel, H., E-mail: harungul@duzce.edu.tr [Duzce University, Gumusova Vocational School, Department of Metallurgy, 81850, Duzce (Turkey); K Latin-Small-Letter-Dotless-I l Latin-Small-Letter-Dotless-I c, F.; Uysal, M.; Aslan, S.; Alp, A.; Akbulut, H. [Sakarya University, Engineering Faculty, Department of Metallurgical and Materials Engineering, Esentepe Campus, 54187, Sakarya (Turkey)

    2012-03-01

    In the present work, a nickel sulfate bath containing SiC submicron particles between 100 and 1000 nm was used as the plating electrolyte. The aim of this work is to obtain Ni-SiC metal matrix composites (MMCs) reinforced with submicron particles on steel surfaces with high hardness and wear resistance for using in anti-wear applications such as dies, tools and working parts for automobiles and vehicles. The influence of the SiC content in the electrolyte on particle distribution, microhardness and wear resistance of nano-composite coatings was studied. During the electroplating process, the proper stirring speed was also determined for sub-micron SiC deposition with Ni matrix. The Ni films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The depositions were controlled to obtain a specific thickness (between 50 and 200 {mu}m) and volume fraction of the particles in the matrix (between 0.02 and 0.10). The hardness of the coatings was measured to be 280-571 HV depending on the particle volume in the Ni matrix. The tribological behaviors of the electrodeposited SiC nanocomposite coatings sliding against an M50 steel ball (O 10 mm) were examined on a tribometer. All the friction and wear tests were performed without lubrication at room temperature and in the ambient air (with a relative humidity of 55-65%). The results showed that the wear resistance of the nanocomposites was approximately 2-2.2 times more than those of unreinforced Ni.

  12. Can infrared spectroscopy be used to measure change in potassium nitrate concentration as a proxy for soil particle movement

    NARCIS (Netherlands)

    Luleva, M.I.; Werff, H.M.A. van der; Jetten, V.G.; Meer, F.D. van der

    2011-01-01

    Displacement of soil particles caused by erosion influences soil condition and fertility. To date, the cesium 137 isotope (137Cs) technique is most commonly used for soil particle tracing. However when large areas are considered, the expensive soil sampling and analysis present an obstacle. Infrared

  13. Effect of particle size and concentration on the mechanical properties of polyester/date palm seed particulate composites

    Directory of Open Access Journals (Sweden)

    Alewo Opuada AMEH

    2015-05-01

    Full Text Available The use of cellulosic materials as reinforcement in composites can greatly enhance their properties. The thrust of this study was to investigate the effect of date palm seed particle on the properties of reinforced polyester. Unsaturated polyester resin was reinforced with date palm seed particles of 0.5, 2.0 and 2.8mm particle sizes using variable particle loadings of 5, 10, 15, 20 and 25wt%. The composites obtained were subjected to various types of mechanical and physical tests in order to assess their performance. The optimum tensile strength of 16.7619N/mm2 and elastic modulus of 343.8N/mm2 were attained at 15wt% and 10wt% loading (using 0.5mm particles respectively and percent water absorption was found to be least for 0.5mm particle size. The hardness was enhanced to the maximum of 74 HRF (Rockwell Hardness Factor by 2mm particle size at 25wt% loading. Pure unsaturated polyester resin recorded tensile strength of 17.5959N/mm2, elastic modulus of 316.7N/mm2 and hardness of 33.5 HRF. The results indicated that the use of date palm seed particles as reinforcement can enhance the properties of polyester composites.

  14. Can infrared spectroscopy be used to measure change in potassium nitrate concentration as a proxy for soil particle movement

    NARCIS (Netherlands)

    Luleva, M.I.; Werff, H.M.A. van der; Jetten, V.G.; Meer, F.D. van der

    2011-01-01

    Displacement of soil particles caused by erosion influences soil condition and fertility. To date, the cesium 137 isotope (137Cs) technique is most commonly used for soil particle tracing. However when large areas are considered, the expensive soil sampling and analysis present an obstacle. Infrared

  15. Elevated levels of triglycerides and vldl-cholesterol provoke activation of nlrp1 inflammasome in endothelial cells.

    Science.gov (United States)

    Bleda, Silvia; de Haro, Joaquin; Varela, Cesar; Ferruelo, Antonio; Acin, Francisco

    2016-10-01

    Soluble stimuli present in the plasma of patients with peripheral arterial disease (PAD) are capable of directly stimulating intracellular signalling in endothelium. Oxidized-LDL (oxLDL) induces NLRP3 inflammasome activation in macrophages. However, it is not clear how lipid profile affect NLRP1 inflammasome gene expression in endothelial cells. In this study, the effect of cholesterol and TG of plasma of patients with PAD on NLRP1 inflammasome gene expression in human arterial endothelial cells (HAECS) was assessed. We included 113 patients with symptomatic PAD. HAECs were stimulated for 2h using the plasma samples of the study participants. The NLRP1 quantification of the transcription was carried out on the 7500 real-time PCR system using the Taqman® Universal PCR Master Mix and Assays on demand. Relative quantification of the NLRP1 expression was carried out using the ΔΔCt (threshold cycle) comparative method. Plasma from patients with elevated VLDL-cholesterol levels (>33.6mg/dL, the median value of the sample) provoked a higher expression of NLRP1 inflammasome in HAECs (RQ=1.15±0.23 vs. 1.05±0.69; p=0.045), as well as plasma from patients with elevated TGs levels (>168mg/dL, the median value of the sample) (RQ=1.15±0.23 vs. 1.05±0.69; p=0.045). A positive correlation was found between NLRP1 inflammasome expression and VLDL-cholesterol plasma levels (r=0.4; pcholesterol of patients with atherosclerosis, manifested as PAD, promote the in vitro NLRP1 inflammasome expression in HAECs. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  16. Oscillatory rheology and creep behavior of barley β-D-glucan concentrate dough: effect of particle size, temperature, and water content.

    Science.gov (United States)

    Ahmed, Jasim; Thomas, Linu; Al-Attar, Hasan

    2015-01-01

    Small amplitude oscillatory rheology and creep behavior of β-glucan concentrate (BGC) dough were studied as function of particle size (74, 105, 149, 297, and 595 μm), BGC particle-to-water ratio (1:4, 1:5, and 1:6), and temperature (25, 40, 55, 70, and 85 °C). The color intensity and protein content increased with decreasing particle size by creating more surface areas. The water holding capacity (WHC) and sediment volume fraction increased with increasing particle size from 74 to 595 μm, which directly influences the mechanical rigidity and viscoelasticity of the dough. The dough exhibited predominating solid-like behavior (elastic modulus, G' > viscous modulus, G″). A discrete retardation spectrum is employed to the creep data to obtain retardation time and compliance parameters, which varied significantly with particle size and the process temperature. Creep tests exhibited more pronounced effect on dough behavior compared to oscillatory measurement. The protein denaturation temperature was insignificantly increased with particle fractions from 107 to 110 °C. All those information could be helpful to identify the particle size range and WHC of BGC that could be useful to produce a β-d-glucan enriched designed food. © 2014 Institute of Food Technologists®

  17. Occurrence of gaseous and particulate polycyclic aromatic hydrocarbons in the urban atmosphere: study of sources and ambient temperature effect on the gas/particle concentration and distribution

    Energy Technology Data Exchange (ETDEWEB)

    Tsapakis, Manolis [Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, EL-71409 Heraklion (Greece); Stephanou, Euripides G. [Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, EL-71409 Heraklion (Greece)]. E-mail: stephanou@chemistry.uoc.gr

    2005-01-01

    The presence of polycyclic aromatic hydrocarbons (PAHs) in an urban region (Heraklion, Greece) and processes that govern their atmospheric fate were studied from November 2000 until February 2002. Sixteen samples were collected, by using an artifact-free sampling device, on a monthly basis and the concentration of PAHs in gas and particulate phase was determined. The most abundant members (gas + particles) were phenanthrene (20.0 {+-} 7.0 ng m{sup -3}), fluoranthene (6.5 {+-} 1.7 ng m{sup -3}), pyrene (6.6 {+-} 2.4 ng m{sup -3}), and chrysene (3.1 {+-} 1.5 ng m{sup -3}). Total concentration (gas + particulate) of PAH ranged from 44.3 to 129.2 ng m{sup -3}, with a mean concentration of 79.3 ng m{sup -3}. Total concentration of PAHs in gas phase ranged from 31.4 to 84.7 ng m{sup -3} with non-observable seasonal variation. Conversely, maximum PAH concentrations in the particulate phase occurred during winter months. Particulate concentration varied from 11.4 to 44.9 ng m{sup -3}, with an average of 25.2 ng m{sup -3}. PAH distribution between gas and particulate phase was in agreement with the sub-cooled vapor pressure. Shift in gas/particle distribution due to difference in ambient temperature elucidated to some extent the seasonal variation of the concentration of PAHs in particles. - Capsule: Ambient PAH partitioning between gas and particle phases vary between compounds and with environmental conditions.

  18. Acute Central Neuropeptide Y Administration Increases Food Intake but Does Not Affect Hepatic Very Low-Density Lipoprotein (Vldl) Production in Mice

    NARCIS (Netherlands)

    Geerling, J.J.; Wang, Y.; Havekes, L.M.; Romijn, J.A.; Rensen, P.C.N.

    2013-01-01

    Objective: Central neuropeptide Y (NPY) administration stimulates food intake in rodents. In addition, acute modulation of central NPY signaling increases hepatic production of very low-density lipoprotein (VLDL)-triglyceride (TG) in rats. As hypertriglyceridemia is an important risk factor for athe

  19. Acute inhibition of hepatic beta-oxidation in APOE*3Leiden mice does not affect hepatic VLDL secretion or insulin sensitivity

    NARCIS (Netherlands)

    Duivenvoorden, [No Value; Teusink, B; Rensen, PCN; Kuipers, F; Romijn, JA; Havekes, LM; Voshol, PJ

    2005-01-01

    Hepatic VLDL and glucose production is enhanced in type 2 diabetes and associated with hepatic steatosis. Whether the derangements in hepatic metabolism are attributable to steatosis or to the increased availability of FA metabolites is not known. We used methyl palmoxirate ( MP), an inhibitor of ca

  20. IRE1α-XBP1s induces PDI expression to increase MTP activity for hepatic VLDL assembly and lipid homeostasis.

    Science.gov (United States)

    Wang, Shiyu; Chen, Zhouji; Lam, Vivian; Han, Jaeseok; Hassler, Justin; Finck, Brian N; Davidson, Nicholas O; Kaufman, Randal J

    2012-10-03

    The unfolded protein response (UPR) is a signaling pathway required to maintain endoplasmic reticulum (ER) homeostasis and hepatic lipid metabolism. Here, we identify an essential role for the inositol-requiring transmembrane kinase/endoribonuclease 1α (IRE1α)-X box binding protein 1 (XBP1) arm of the UPR in regulation of hepatic very low-density lipoprotein (VLDL) assembly and secretion. Hepatocyte-specific deletion of Ire1α reduces lipid partitioning into the ER lumen and impairs the assembly of triglyceride (TG)-rich VLDL but does not affect TG synthesis, de novo lipogenesis, or the synthesis or secretion of apolipoprotein B (apoB). The defect in VLDL assembly is, at least in part, due to decreased microsomal triglyceride-transfer protein (MTP) activity resulting from reduced protein disulfide isomerase (PDI) expression. Collectively, our findings reveal a key role for the IRE1α-XBP1s-PDI axis in linking ER homeostasis with regulation of VLDL production and hepatic lipid homeostasis that may provide a therapeutic target for disorders of lipid metabolism.

  1. Hepatic VLDL production in ob/ob mice is not stimulated by massive de novo lipogenesis but is less sensitive to the suppressive effects of insulin

    NARCIS (Netherlands)

    Wiegman, CH; Bandsma, RHJ; Ouwens, M; van der Sluijs, FH; Havinga, R; Boer, T; Reijngoud, DJ; Romijn, JA; Kuipers, F

    Type 2 diabetes in humans is associated with increased de novo lipogenesis (DNL), increased fatty acid (FA) fluxes, decreased FA oxidation, and hepatic steatosis. In this condition, VLDL production is increased and resistant to suppressive effects of insulin. The relationships between hepatic FA

  2. Tumor necrosis factor-alpha directly stimulates the overproduction of hepatic apolipoprotein B100-containing VLDL via impairment of hepatic insulin signaling.

    Science.gov (United States)

    Insulin resistant states are commonly associated with both increased circulating levels of tumor necrosis factor (TNF-a) and hepatic overproduction of very low density lipoproteins (VLDL). In the present study, we examined the potential mechanistic link between TNF-a and hepatic overproduction of ap...

  3. The coffee diterpene cafestol increases plasma triacylglycerol by increasing the production rate of large VLDL apolipoprotein B in healthy normolipidemic subjects

    NARCIS (Netherlands)

    Roos, de B.; Caslake, M.J.; Stalenhoef, A.F.H.; Bedford, D.; Demacker, P.N.; Katan, M.B.; Packard, C.J.

    2001-01-01

    Background: Cafestol is a diterpene in unfiltered coffee that raises plasma triacylglycerol in humans. Objective: We studied whether cafestol increases plasma triacylglycerol by increasing the production rate or by decreasing the fractional catabolic rate of VLDL1 [Svedberg flotation unit (Sf) 60-40

  4. Single-Particle Tracking of Human Lipoproteins.

    Science.gov (United States)

    de Messieres, Michel; Ng, Abby; Duarte, Cornelio J; Remaley, Alan T; Lee, Jennifer C

    2016-01-05

    Lipoproteins, such as high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very-low density lipoprotein (VLDL), play a critical role in heart disease. Lipoproteins vary in size and shape as well as in their apolipoprotein content. Here, we developed a new experimental framework to study freely diffusing lipoproteins from human blood, allowing analysis of even the smallest HDL with a radius of 5 nm. In an easily constructed confinement chamber, individual HDL, LDL, and VLDL particles labeled with three distinct fluorophores were simultaneously tracked by wide-field fluorescence microscopy and their sizes were determined by their motion. This technique enables studies of individual lipoproteins in solution and allows characterization of the heterogeneous properties of lipoproteins which affect their biological function but are difficult to discern in bulk studies.

  5. A history of previous gestational diabetes mellitus is associated with adverse changes in insulin secretion and VLDL metabolism independently of increased intrahepatocellular lipid.

    Science.gov (United States)

    Forbes, S; Godsland, I F; Taylor-Robinson, S D; Bell, J D; Thomas, E L; Patel, N; Hamilton, G; Parker, K H; Marshall, I; Gray, C D; Bedford, D; Caslake, M; Walker, B R; Johnston, D G

    2013-09-01

    We have previously reported a high prevalence of non-alcoholic fatty liver disease (NAFLD) among women with previous gestational diabetes mellitus (pGDM). We wanted to confirm that intrahepatocellular lipid (IHCL) is associated with pGDM independently of adiposity and determine: (1) if VLDL metabolism is dysregulated; and (2) the extent to which NAFLD and IHCL account for the dysmetabolic phenotype in pGDM. We analysed data from a cohort of 234 women (114 with pGDM) and identified effects of pGDM on lipid and glucoregulation that were independent of ultrasound-diagnosed NAFLD. We then measured IHCL by MR spectroscopy in a representative subgroup (n = 36) and conducted detailed metabolic studies (IVGTT, VLDL apolipoprotein B [apoB] kinetics and palmitate turnover) and measurement of regional body fat by MRI to demonstrate effects of IHCL that were independent of a history of pGDM. pGDM was associated with increased IHCL (p = 0.04) after adjustment for adiposity. Independently of IHCL, pGDM was associated with a lower IVGTT disposition index (p = 0.02) and acute insulin response to glucose (pGDM+/NAFLD-, 50% lower; pGDM+/NAFLD+, 36% lower; effect of pGDM, p = 0.03), increased VLDL apoB pool size (pGDM+/NAFLD-, 3.1-fold higher; pGDM+/NAFLD+, 1.2-fold higher; effect of pGDM, p = 0.02) and, at borderline significance (p = 0.05), increased rate of VLDL apoB synthesis. pGDM is associated with increased IHCL independently of adiposity. The increased liver fat contributes to the phenotype, but pGDM status is independently associated with diminished insulin secretion and (shown for the first time) augmented VLDL metabolism. IHCL with pGDM may compound a dysmetabolic phenotype.

  6. Variable production of transparent exopolymeric particles by haploid and diploid life stages of coccolithophores grown under different CO2 concentrations

    NARCIS (Netherlands)

    Pedrotti, M.L.; Fiorini, S.; Kerros, M.E.; Middelburg, J.J.; Gattuso, J.P.

    2012-01-01

    The production of transparent exopolymeric particles (TEP) by the coccolithophores, Emiliania huxleyi, Calcidiscus leptoporus and Syracosphaera pulchra was investigated in batch cultures. The abundance, size spectra and carbon content of TEP were examined during the exponential growth phase of both

  7. Single-particle inductively coupled plasma mass spectroscopy analysis of size and number concentration in mixtures of monometallic and bimetallic (core-shell) nanoparticles.

    Science.gov (United States)

    Merrifield, Ruth C; Stephan, Chady; Lead, Jamie R

    2017-01-01

    It is challenging to separate and measure the physical and chemical properties of monometallic and bimetallic engineered nanoparticles (NPs), especially when mixtures are similar in size and at low concentration. We report that single particle inductively coupled mass spectroscopy (SP-ICP-MS), alongside field flow fractionation (FFF), has allowed for the accurate measurement of size and particle number concentrations of mixed metallic nanoparticles (NPs) containing monometallic NPs of gold (Au) and silver (Ag) and a bimetallic core-shell structured NP (Au@Ag) of equivalent size. Two sets of these NPs were measured. The first contained only 60nm particles, where the Au@Ag NP had a 30nm core and 15nm shell to make a total diameter of 60nm. The second contained only 80nm particles (Au@Ag NP core particle of 50nm with a 15nm shell). FFF separation was used here as a sizing technique rather than a separation technique. It was used to confirm that suspensions containing either individual or mixtures of the Au 60nm, Ag 60nm and AuAg 60nm suspensions eluted together and were of the same size. Similarly, FFF was used to show that suspensions containing individual or mixtures of the equivalent 80nm, eluted together and were of the same size. Although the 60nm and 80nm suspensions did not elute at the same time they were not run together. SP-ICP-MS is then used to identify the size and concentration of the particles within the suspension. Successful separation of the NPs was effected and the limits of the instrument were obtained. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Analysis on Concentration and Source Rate of Precursor Vapors Participating in Particle Formation and Growth at Xinken in the Pearl River Delta of China

    Institute of Scientific and Technical Information of China (English)

    GONG Youguo; SU Hang; CHENG Yafang; LIU Feng; WU Zhijun; HU Min; ZENG Limin; ZHANG Yuanhang

    2008-01-01

    Concentration and source rate of precursor vapors participating in particle formation and subsequent growth were investigated during the Pearl River Delta intensive campaign (PRD2004, October 2004) in southeastern China. Four new particle formation event days and a typical non-event day were selected for our analysis. Atmospheric sulphuric acid, the important precursor vapor in nucleation and growth, were simulated with a pseudo steady-state model based on the measurements of SO2, NOX, O3, CO, non-methane hydrocarbon (NMHC) and ambient particle number concentrations as well as modeled photolysis frequencies obtained from measurements. The maximum midday sulphuric acid concentrations vary from 4.53 × 107 to 2.17 × 108 molecules cm-3, the corresponding source rate via reaction of OH and SO2 range between 2.37 × 106 and 1.16 × 107 molecules cm-3 s-1. Nucleation mode growth rate was derived from size spectral evolution during the events to be 6.8-13.8 nm h-1. Based on the growth rate, concentration of the vapors participating in subsequent growth were estimated to vary from 1.32 × 10s to 2.80 × 108 molecules cm-3 with corresponding source rate between 7.26 × 106 and 1.64 × 107 molecules cm-3 s-1. Our results show the degree of pollution is larger in PRD. Sulphuric acid concentrations are fairly high and have a close correlation with new particle formation events. Budget analysis shows that sulphuric acid alone is not enough for required growth; other nonvolatile vapors are needed. However, sulphuric acid plays an important role in growth; the contribution of sulphuric acid to growth in PRD is 12.4%-65.2%.

  9. The relationship between aerosol particles chemical composition and optical properties to identify the biomass burning contribution to fine particles concentration: a case study for São Paulo city, Brazil.

    Science.gov (United States)

    de Miranda, Regina Maura; Lopes, Fabio; do Rosário, Nilton Évora; Yamasoe, Marcia Akemi; Landulfo, Eduardo; de Fatima Andrade, Maria

    2016-12-01

    The air quality in the Metropolitan Area of São Paulo (MASP) is primarily determined by the local pollution source contribution, mainly the vehicular fleet, but there is a concern about the role of remote sources to the fine mode particles (PM2.5) concentration and composition. One of the most important remote sources of atmospheric aerosol is the biomass burning emissions from São Paulo state's inland and from the central and north portions of Brazil. This study presents a synergy of different measurements of atmospheric aerosol chemistry and optical properties in the MASP in order to show how they can be used as a tool to identify particles from local and remote sources. For the clear identification of the local and remote source contribution, aerosol properties measurements at surface level were combined with vertical profiles information. Over 15 days in the austral winter of 2012, particulate matter (PM) was collected using a cascade impactor and a Partisol sampler in São Paulo City. Mass concentrations were determined by gravimetry, black carbon concentrations by reflectance, and trace element concentrations by X-ray fluorescence. Aerosol optical properties were studied using a multifilter rotating shadowband radiometer (MFRSR), a Lidar system and satellite data. Optical properties, concentrations, size distributions, and elemental composition of atmospheric particles were strongly related and varied according to meteorological conditions. During the sampling period, PM mean mass concentrations were 17.4 ± 10.1 and 15.3 ± 6.9 μg/m(3) for the fine and coarse fractions, respectively. The mean aerosol optical depths at 415 nm and Ångström exponent (AE) over the whole period were 0.29 ± 0.14 and 1.35 ± 0.11, respectively. Lidar ratios reached values of 75 sr. The analyses of the impacts of an event of biomass burning smoke transport to the São Paulo city revealed significant changing on local aerosol concentrations and optical parameters

  10. Concentration of lead, cadmium, and iron in sediment dust and total suspended particles before and after initialisation of integral production in iron and steel work plant Zenica.

    Science.gov (United States)

    Prcanović, Halim; Duraković, Mirnes; Beganović, Sanela

    2012-06-01

    Poor air quality is a common fact for all areas with base industry. The city of Zenica was once the metallurgical centre of Ex-Yugoslavia and is therefore highly polluted at present. Air pollution peaked in 1987 when average concentration of pollutants was extremely high (daily average concentration of SO(2) was 1800 μg m(-3)). With the beginning of the war in 1992, integral production in the steel work plant was shut down, to be re-launched in 2008. Limit values for iron do not exist, but iron has been monitored in Zenica for the past 28 years because of the presence of steel works. Concentrations of cadmium and lead have also been measured because they are very much present in polluted areas with steel works. The concentration of mentioned elements in air deposit and total suspended particles before and after integral production in the steel work plant was re-launched is the subject of this paper. Total suspended particles were measured in two locations using German standard VDI 2463 Blatt 4. Sediment dust was measured in nine locations using Bergerhoff method. The concentration of iron, lead, and cadmium was performed in the chemical laboratory of the Metallurgical Institute "Kemal Kapetanović" Zenica using standard methods. Higher concentrations of these parameters during the period of integral production clearly point to the impact of steel works on Zenica valley.