Change In Number Of Particles Research Articles

Study on the Effect of Secondary Injection on the Combustion and Emission of n-Butanol Engines.

n-Butanol, as a biological alternative fuel containing oxygen, has similar physical and chemical properties to gasoline and has a wide range of sources, which has attracted more and more attention and research. Direct injection technology has been widely used in the field of internal combustion engine due to its advantages of flexibility and control ability. In this paper, the secondary injection of n-butanol engine under the mode of in-cylinder direct injection is discussed to organize stratified combustion of the mixture, optimize combustion to improve the thermal efficiency, and reduce emission. A four-cylinder four-stroke spark ignition (SI) engine was selected to carry out the secondary injection experiment of n-butanol under the excess air ratio (λ) of 1, an engine speed of 1500 r/min, and a low load, and the variables were the second injection ratio and timing. The results show that the secondary injection of n-butanol can achieve stratified combustion of the mixture, but only at a specific second injection timing such as 100°CA before compression top dead center (BTDC) or 125°CA BTDC, the combustion effect is the best. A small second injection ratio can optimize combustion, improve brake thermal efficiency, and reduce hydrocarbon and carbon monoxide emissions. When the second injection ratio is greater than 60%, it results in incomplete fuel combustion, a 3 to 4% reduction in thermal efficiency, and an increase in emissions. Coefficient of variation (COV) was increased by secondary injection, but the effect was insignificant in the small injection ratio, and it will increase with the increase of the second injection ratio. The change of particle number is mainly affected by the nuclear particle number, and with the increase of the second injection ratio, the total particulate number is more affected by the second injection timing. The second injection ratio of 40% can reduce the total particle number under the mixed-gas stratification condition.

Study on Gas-solid Two-phase Flow Field of Ramon Mill Classifier

To reveal the working principle and internal flow field law of the grading machine, the numerical simulation of the gas-solid two-phase flow field was carried out. In this paper, the numerical simulation method based on Fluent is used to obtain the internal velocity distribution and pressure distribution of the grading machine. The flow field of gas-solid two-phase was studied based on the CFD-DEM coupling, and the particle motion trajectory in the grading machine and the particle motion law in the flow field at different times were obtained; The influence of the operating parameters of the internal flow field on the force of particles in the grading machine was analyzed, and combined with the change of particle number, the particle collection efficiency of the grading machine under different operating parameters was further given. It is of guiding significance to adjust the parameters of the grading machine, improve the output and the product quality of the longitudinal mill, and reduce the energy consumption of the longitudinal mill.

Establishment of nucleation and growth model of silica nanostructured particles and comparison with experimental data

A mathematical model is developed for the calculation of the nucleation and growth process of silica nanostructured particles prepared by using the drop-by-drop method, and the calculation results of the proposed model is compared with the experimental value obtained from SAXS data. The model provides a non-ideal improvement in the supersaturation calculation and considers the impact of both mass transfer and surface reaction on the particle growth rate. The nucleation and growth rates are coupled depending on the change in monomer concentration over time, based on which the particle size and distribution are calculated. The growth curve of the silica particles from 3 nm to 20 nm and the change in particle number from 0 to over 10 20 are calculated, which are consistent with the experimental values, establishing the reliability of the model. The calculations of the growth rate reveal that mass transfer controls the growth of silica particles before 10 min and the surface reaction is the rate-determining step after 10 min. The changes in the model parameters obtained by fitting with the SAXS data under different reaction conditions indicate the sensitivity of the corresponding process to different conditions. Moreover, the relationship between the particle growth rate and monomer concentration change is analyzed using the proposed model.

Collective Excitations and Nonequilibrium Phase Transition in Dissipative Fermionic Superfluids.

We predict a new mechanism to induce collective excitations and a nonequilibrium phase transition of fermionic superfluids via a sudden switch on of two-body loss, for which we extend the BCS theory to fully incorporate a change in particle number. We find that a sudden switch on of dissipation induces an amplitude oscillation of the superfluid order parameter accompanied by a chirped phase rotation as a consequence of particle loss. We demonstrate that when dissipation is introduced to one of the two superfluids coupled via a Josephson junction, it gives rise to a nonequilibrium dynamical phase transition characterized by the vanishing dc Josephson current. The dissipation-induced collective modes and nonequilibrium phase transition can be realized with ultracold fermionic atoms subject to inelastic collisions.

Chemical Composition of Gas and Particle Phase Products of Toluene Photooxidation Reaction under High OH Exposure Condition

In the current study, the photooxidation reaction of toluene (C7H8) was investigated in a Potential Aerosol Mass Oxidation Flow Reactor (PAM OFR). The hydroxyl radical (OH) exposure of toluene in the PAM OFR ranged from 0.4 to 1.4 × 1012 molec cm−3 s, which is equivalent to 3 to 12 days of atmospheric oxidation. A proton transfer reaction-mass spectrometer (PTR-MS) and a scanning mobility particle sizer (SMPS) were used to study the gas-phase products formed and particle number changes of the oxidation reaction in PAM OFR. The secondary organic aerosol (SOA) formed in the PAM OFR was also collected for off-line chemical analysis. Key gas-phase reaction products of toluene, including glyoxal, methyl glyoxal, unsaturated carbonyl compounds, and benzaldehyde, were identified by the PTR-MS. Second generation products, including acetic acid, formaldehyde, formic acid, and acetaldehyde, were also detected. By comparing the mass spectrums obtained under different OH exposures and relative humidity (RH), changes in the two parameters have minimal effects on the composition of gas-phase products formed, expect for the spectrum obtained at OH exposure of 0.4 × 1012 cm−3 s and RH = 17%, which is slightly different from other spectrums. SMPS results showed that particle mass concentration increases with increasing OH exposure, while particle number concentration first increases and then decreases with increasing OH exposure. This result probably suggests the formation of oligomers at high OH exposure conditions. Off-line chemical analysis of the SOA sample was dominated by C4 diacids, including malic acid, citramalic acid, and tartaric acid. The well-known toluene SOA marker 2,3-Dihydroxy-4-oxopentanoic acid, as well as 2,3-dihydroxyglutaric acid, which has not been identified in previous toluene photooxidation experiments, were also detected in the SOA sample. Our results showed good agreements with the results of previous smog chamber studies of toluene photooxidation reaction, and they suggested that using PAM OFR for studies of oxidation reaction of different VOCs can be atmospherically relevant.

HDL, apo a1 and long-term cardio-metabolic prognosis in statin-treated patients with suspected stable angina pectoris: a prospective cohort study

Abstract Background Reduced serum levels of high density lipoprotein cholesterol (HDL-C) is a hallmark of the metabolic syndrome. Epidemiologic studies have reported an inverse correlation between HDL- C and cardiovascular disease (CVD) risk. However, recent works suggest that the association is strongest in healthy individuals. Changes in particle number and functional properties of HDL may more closely reflect CVD prognosis in patients with pre-existent disease. The majority of such patients receive statin treatment, which affects both HDL-C levels, and particle composition. Hence, serum apoA1 and the HDL-C:apoA1 ratio have been proposed as more sensitive indicators of cardio-metabolic prognosis. Purpose We studied the associations of serum HDL-C, apoA1 and the HDL-C: apoA1 ratio to long term risk of CVD mortality and incident type 2 diabetes (T2D) patients with suspected stable angina pectoris (SAP). Methods A total of 41064 patients underwent elective coronary angiography in 2000–2004 and were followed-up for CVD mortality throughout 2016. In a subgroup of 2519 participants without verified or possible diabetes at baseline, the associations to incident type 2 diabetes (T2D) were evaluated throughout 2014. Information on clinical endpoints was obtained through national health registries. Risk estimates are reported per 1 SD increment of (log transformed) biomarkers and were calculated by cox or logistic regression. We explored risk classification by calculating the continuous net reclassification improvement (NRI). Results At inclusion, median (25th-75th percentiles) age was 62 (55–70) years, 28% were women 76% had obstructive coronary artery disease and 80% received statins. During median (25th-75th percentiles) 13.9 (12.0–15.3) years of follow-up, 14.1% of the participants died from CVD. After multivariate adjustment (age, gender, body mass index, HbA1c, triglycerides, statin treatment, fasting status) HDL and apoA1, but not the HDL: apoA1 ratio, significantly predicted CVD mortality. The hazard ratio (HR) and 95% confidence interval (CI) was: 0.86 (0.78–0.94), 0.88 (0.80–0.98) and 0.96 (0.86–1.03) for HDL-C, apoA1 and the HDL-C:apoA1 ratio, respectively. HDL-C was the only of the evaluated biomarkers providing a significant NRI (95% CI) of 0.14 (0.04–0.19). In the subset evaluated for incdent T2D, HDL-C provided multivariate adjusted odds ratios (OR; 95% CI) and NRI (95% CI) of 0.69 (0.58–0.82) and 0.34 (0.21–0.47) for new onset TSD. The corresponding OR (95% CI) and NRI (95% CI) for apoA1 were: 0.85 (0.73–0.99) and 0.20 (0.06–0.33), respectively. The HDL:apo A1 ratio provided an OR (95% CI) of 0.66 (0.55–0.80) and NRI (95% CI) of 0.24 (0.11–0.37) for T2D. No significant effect modifications according to statin treatment were found (P≥0.22). Conclusion Among patients with suspected SAP, of which the majority received statins, HDL-C was non-inferior to apoA1 and the HDL:apoA1 ratio in predicting long term risk of CVD mortality and T2D. Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): Department of Heart Disease, Haukeland University Hospital; Department of Clinical Science, University of Bergen

2D Diffusion-Ordered 1 H-NMR Spectroscopy Lipidomic Profiling after Oral Single Macronutrient Loads: Influence of Obesity, Sex, and Female Androgen Excess.

Postprandial dysmetabolism plays a major role in the pathogenesis of metabolic disorders such as obesity and the polycystic ovary syndrome (PCOS). The aim is to characterize the circulating lipoprotein particle profiles in response to oral glucose, lipid, and protein challenges. 17 women with PCOS, 17 control women, and 19 healthy men selected to have similar age and body mass index are studied. Blood samples are collected following the ingestion of 300kcal in the form of glucose, lipids, or proteins, and they are submitted to two-dimensional (2D) diffusion-ordered 1 H-NMR spectroscopy. Regardless of macronutrient administered, the number of very low-density (VLDL) particles increases whereas low density-lipoprotein (LDL) decreases. High density-lipoprotein (HDL) particles increase only after lipid ingestion. Obese subjects show an increase in the number of large VLDL particles and a decrease in large LDL particles, with a significant reduction in the average particle size of LDL. Patients with PCOS show a particularly unfavorably smaller LDL particle size response to oral lipid intake, regardless of obesity. Oral macronutrient challenges induce immediate class-specific postprandial changes in particle number and size of lipoproteins, with lipids inducing a more pro-atherogenic lipoprotein profile compared to glucose and proteins, particularly in obese subjects and women with PCOS.

The Resolvent Algebra of Non-relativistic Bose Fields: Sectors, Morphisms, Fields and Dynamics

It was recently shown that the resolvent algebra of a non-relativistic Bose field determines a gauge invariant (particle number preserving) kinematical algebra of observables which is stable under the automorphic action of a large family of interacting dynamics involving pair potentials. In the present article, this observable algebra is extended to a field algebra by adding to it isometries, which transform as tensors under gauge transformations and induce particle number changing morphisms of the observables. Different morphisms are linked by intertwiners in the observable algebra. It is shown that such intertwiners also induce time translations of the morphisms. As a consequence, the field algebra is stable under the automorphic action of the interacting dynamics as well. These results establish a concrete C*-algebraic framework for interacting non-relativistic Bose systems in infinite space. It provides an adequate basis for studies of long range phenomena, such as phase transitions, stability properties of equilibrium states, condensates, and the breakdown of symmetries.

Permeability of immobile rings of membrane inclusions to in-plane flow.

We study the flow of membranal fluid through a ring of immobile particles mimicking, for example, a fence around a membrane corral. We obtain a simple closed-form expression for the permeability coefficient of the ring as a function of the particles' line fraction. The analytical results agree with those of numerical calculations and are found to be robust against changes in particle number and corral shape. From the permeability results, we infer the collective diffusion coefficient of lipids through the ring and discuss possible implications for collective lipid transport in a crowded membrane.

A Combined Spin-Flip and IP/EA Approach for Handling Spin and Spatial Degeneracies: Application to Double Exchange Systems.

Many multiconfigurational systems, such as single-molecule magnets, are difficult to study using traditional computational methods due to the simultaneous existence of both spin and spatial degeneracies. In this work, a new approach termed n-spin-flip ionization potential/electron affinity ( nSF-IP or nSF-EA) is introduced which combines the spin-flip method of Anna Krylov with particle-number changing IP/EA methods. We demonstrate the efficacy of the approach by applying it to the strongly correlated N2+, as well as several double exchange systems. We also demonstrate that when these systems are well-described by a double exchange model Hamiltonian, only 1SF-IP/EA is required to extract the double exchange parameters and accurately predict energies for the low-spin states. This significantly reduces the computational effort for studying such systems. The effects of including additional excitations (using a RAS- nSF-IP/EA scheme) are also examined, with particular emphasis on hole and particle excitations.

Quantum walks assisted by particle-number fluctuations

We study the spreading of a quantum particle placed in a single site of a lattice or binary tree with the Hamiltonian permitting particle-number changes. We show that the particle-number-changing interactions accelerate the spreading beyond the ballistic expansion limit by inducing off-resonant Rabi oscillations between states of different numbers of particles. We consider the effect of perturbative number-changing couplings on Anderson localization in one-dimensional disordered lattices and show that they lead to decrease of localization. The effect of these couplings is shown to be larger at larger disorder strength, which is a consequence of the disorder-induced broadening of the particle dispersion bands.

Challenges for semilocal density functionals with asymptotically nonvanishing potentials

The Becke-Johnson model potential [A. D. Becke and E. R. Johnson, J. Chem. Phys. 124, 221101 (2006)] and the potential of the AK13 functional [R. Armiento and S. K\"ummel, Phys. Rev. Lett. 111, 036402 (2013)] have been shown to mimic features of the exact Kohn-Sham exchange potential, such as step structures that are associated with shell closings and particle-number changes. A key element in the construction of these functionals is that the potential has a limiting value far outside a finite system that is a system-dependent constant rather than zero. We discuss a set of anomalous features in these functionals that are closely connected to the nonvanishing asymptotic potential. The findings constitute a formidable challenge for the future development of semilocal functionals based on the concept of a nonvanishing asymptotic constant.

Optical properties of cirrus transition zones over China detected by CALIOP

A transition zone near cirrus lateral boundaries can be detected by CALIOP (cloud–aerosol lidar with orthogonal polarization). In the present study, for such transition zones over China, a number of optical properties, such as the backscatter coefficient and depolarization ratio, showed transitional characteristics between cirrus and clear sky. The stepped horizontal profile showed sharp changes in particle number and morphology between cirrus clouds and clear sky. The color ratio, however, was unable to show cirrus transition features because of the low signal-to-noise ratio. Typical ice particles presented a color ratio of 0.55–1.25 and a depolarization ratio of greater than 0.12, which were significantly higher than those of clear sky. Therefore, optical properties in transition took the form of stepwise horizontal profiles. The proportion of typical-featured particles also demonstrated a stepped horizontal profile similar to the optical characteristics, but the relationship between the proportion and the optical characteristics was not uniform in the cirrus clouds, transition zone, and clear sky. Therefore, the optical changes in the transition zone were caused by not only the change in particle concentration, but also the change in the particles themselves. The probability density distribution of the transition-zone widths showed a positive skewness distribution, and transition zones with widths of 3–5 km occurred most frequently. Overall, transition-zone width decreased with increasing temperature and increased with increasing vertical and horizontal wind speeds. This trend demonstrated independence with the direction of the vertical and horizontal winds. These observations implied that the transitional features were caused by material exchange, such as entrainment and turbulent transport, near the cirrus lateral boundaries, and by the phase transformation of particles, such as sublimation.

Population Balance Equation of Cohesive Particle Flow in a Circulating Fluidized Bed

AbstractA novel model coupled with a population balance equation is adopted for simulating the aggregation process and flow behavior of cohesive powders in a full‐loop circulating fluidized bed. The agglomerate diameter is calculated according to the change of particle number by a population balance equation which is solved as a part of computational fluid dynamics simulation. The solid pressure and viscosity are redefined by taking the effect of interparticle force into consideration based on the kinetic theory of granular flow. Simulation results of time‐averaged solid volume fraction and diameter of agglomerate are predicted by a numerical method and are in reasonable agreement with experimental data. The variation of mass flux, solid pressure, and viscosity under different operating conditions are analyzed based on the proposed model.

Study of Flow Characteristics of Ultrafine CaCO3 Powders in a Spouted Bed

AbstractThe flow behavior of gas and ultrafine powder in a spouted bed was numerically investigated by using a two‐fluid model coupled with a population balance equation (PBE). The aggregation process is controlled by the PBE, which is solved by the direct quadrature method of moments. The agglomerate diameter is calculated according to the change in particle number. The solid pressure and viscosity were modified for agglomerates on the basis of the kinetic theory of granular flow. Distributions of diameter, solids volume fraction, and velocity are obtained by the new model. The influence of cohesive intensity and gas velocity on the diameter distribution were analyzed. The spout diameter, a vital parameter for the design of spouted beds, was calculated and a calculation formula is proposed.

Field Measurements of Gasoline Direct Injection Emission Factors: Spatial and Seasonal Variability.

Four field campaigns were conducted between February 2014 and January 2015 to measure emissions from light-duty gasoline direct injection (GDI) vehicles (2013 Ford Focus) in an urban near-road environment in Toronto, Canada. Measurements of CO2, CO, NOx, black carbon (BC), benzene, toluene, ethylbenzene-xylenes (BTEX), and size-resolved particle number (PN) were recorded 15 m from the roadway and converted to fuel-based emission factors (EFs). Other than for NOx and CO, the GDI engine had elevated emissions compared to the Toronto fleet, with BC EFs in the 73rd percentile, BTEX EFs in the 80-90th percentile, and PN EFs in the 75th percentile during wintertime measurements. Additionally, for three campaigns, a second platform for measuring PN and CO2 was placed 1.5-3 m from the roadway to quantify changes in PN with distance from point of emission. GDI vehicle PN EFs were found to increase by up to 240% with increasing distance from the roadway, predominantly due to an increasing fraction of sub-40 nm particles. PN and BC EFs from the same engine technology were also measured in the laboratory. BC EFs agreed within 20% between the laboratory and real-world measurements; however, laboratory PN EFs were an order of magnitude lower due to exhaust conditioning.

New cytotoxic butyltin complexes with 2-sulfobenzoic acid: Molecular interaction with lipid bilayers and DNA as well as in vitro anticancer activity

New butyltin complexes with 2-sulfobenzoic acid: [Sn(C4H9)2{O3SC6H4COO-2}(H2O)]·(C2H5OH) (DBTsbz), [Sn(C4H9)3{O3SC6H4COOH-2}] (TBTsbz) and [Sn2(C4H9)6{μ-O3SC6H4COO-2}] (DTBTsbz) are very effective cytotoxic agents against tumor cells. The molecular interaction of these complexes with lipid membranes and DNA has been investigated.The IR spectra and changes of 1H, 13C chemical shifts suggest that SO3 and COO groups of 2-sulfobenzoato ligand interact with O atom of glycerin fragment of DPPC. Moreover, the compounds form Sn–OP bonds with phosphate groups of DPPC, which was shown by the lower frequency shift of the νs(PO2−) and νas(PO2−) band, by change of 31P NMR signals and by DFT calculation. Another possibility is the interaction of the phosphate group of DPPC owing to formation of hydrogen bond O–H…O–P between water molecule coordinated to Sn and oxygen atom from the phosphate group.Using TCSPC-FCS we characterized DNA supramolecular assemblies' formation upon increasing TBTsbz, DTBTsbz and DBTsbz concentration. Diffusion time, lifetime and particle number changes are altered systematically with increasing Ccomp/CDNAbp ratio in following effectiveness order DBTsbz > TBTsbz > DTBTsbz. From those parameters we can conclude that all these compounds lead to a change of DNA winding, strand but not to DNA compaction.Investigated compounds show very high cytotoxic activity against cancer cell lines. All compounds exhibit efficient in vitro antitumor activity toward Jurkat (T-cell leukemia), CL-1 (T-lymphoblastoid cell line), GL-1 (B cell lymphoma cell line) and D-17 (canine osteosarcoma). The DBTsbz is more effective then carboplatin against canine osteosarcoma.

Matter, energy, and heat transfer in a classical ballistic atom pump.

A ballistic atom pump is a system containing two reservoirs of neutral atoms or molecules and a junction connecting them containing a localized time-varying potential. Atoms move through the pump as independent particles. Under certain conditions, these pumps can create net transport of atoms from one reservoir to the other. While such systems are sometimes called "quantum pumps," they are also models of classical chaotic transport, and their quantum behavior cannot be understood without study of the corresponding classical behavior. Here we examine classically such a pump's effect on energy and temperature in the reservoirs, in addition to net particle transport. We show that the changes in particle number, of energy in each reservoir, and of temperature in each reservoir vary in unexpected ways as the incident particle energy is varied.

The iron lung: A device for the continuous delivery of fine particulate matter

In aerosol research, bag-sampling techniques are commonly used for temporary storage of aerosols. They have been used for aging studies and to integrate over fluctuations in aerosol properties and concentrations. Here, we describe the design and operation of an iron lung aerosol sampler consisting of a large volume (∼277 l) drum and a conductive drum liner. This iron lung is used for the continuous delivery of fine particulate matter. Its performance for storage and sampling of fine particulate matter has been evaluated with soot from a kerosene lamp by characterizing the change of particle number and size distribution as function of time with a scanning mobility particle sizer. Changes in these properties have been shown to be smooth, demonstrating the utility of the iron lung described here.

Effect of Ambient Temperature and Fuel on Particle Number Emissions on Light-Duty Spark-Ignition Vehicles

To better understand the impact of ambient temperature and fuel on the emissions of ultrafine particles from spark ignition light-duty vehicles, experiments were conducted to examine the impact of ethanol-gasoline mixtures, compressed natural gas (CNG), and ambient temperature, on the size distribution and number emissions of particles. Vehicles were tested on a chassis dynamometer under controlled conditions of ambient temperature spanning from 60 to 85°F. A dual fuel vehicle operating with CNG and 6% ethanol-gasoline blends (E6); and a flex fuel vehicle operating with four different ethanol-gasoline blends E6, 35% ethanol (E35), 65% ethanol (E65) and 85% ethanol (E85) was evaluated to understand fuel effects. Changes in vehicle operating temperature, which included the combustion air temperature, over the ranges of 60 to 85°F showed no clear impact on fine particle emissions. Likewise, no significant changes in particle number or particle size distributions were observed between CNG and E6 fuels. However, tests with the flex fuel vehicle, which were able to examine higher ethanol concentrations in the fuel showed large decreases in particle number emissions as ethanol levels increased to E65 and E85.