Mean Number Of Particles Research Articles

Thermal aspects of interacting quantum gases in Lorentz-violating scenarios

In this work, we study the interaction of quantum gases in Lorentz-violating scenarios considering both boson and fermion sectors. In the latter case, we investigate the consequences of a system governed by scalar, vector, pseudovector and tensor operators. Besides, we examine the implications of $\left( \hat{k}_{a}\right) ^{\kappa }$ and $\left( \hat{k}_{c}\right) ^{\kappa \xi }$ operators for the boson case as well. For doing so, we regard the grand canonical ensemble seeking the so-called partition function, which suffices to provide analytically the calculations of interest, i.e., mean particle number, entropy, mean total energy and pressure. Furthermore, in low temperature regime, such quantities converge until reaching a similar behavior being in contrast with what is shown in high temperature regime, which brings out the differentiation of their effects. In addition, particle number, entropy and energy exhibit an extensive characteristic even in the presence of Lorentz violation. Finally, for peseudovector and tensor operators, we notice a remarkable feature due to the breaking process of spin degeneracy: the system turns out to have greater energy and particle number for the spin-down particles in comparison with spin-up ones.

Effect of Reducing Ambient Traffic-Related Air Pollution on Blood Pressure: A Randomized Crossover Trial.

Exposure to traffic-related air pollution (TRAP) may contribute to increased prevalence of hypertension and elevated blood pressure (BP) for residents of near-highway neighborhoods. Relatively few studies have investigated the effects of reducing TRAP exposure on short-term changes in BP. We assessed whether reducing indoor TRAP concentrations by using stand-alone high-efficiency particulate arrestance (HEPA) filters and limiting infiltration through doors and windows effectively prevented acute (ie, over a span of hours) increases in BP. Using a 3-period crossover design, 77 participants were randomized to attend three 2-hour-long exposure sessions separated by 1-week washout periods. Each participant was exposed to high, medium, and low TRAP concentrations in a room near an interstate highway. Particle number concentrations, black carbon concentrations, and temperature were monitored continuously. Systolic BP (SBP), diastolic BP, and heart rate were measured every 10 minutes. Outcomes were analyzed with a linear mixed model. The primary outcome was the change in SBP from 20 minutes from the start of exposure. SBP increased with exposure duration, and the amount of increase was related to the magnitude of exposure. The mean change in SBP was 0.6 mm Hg for low exposure (mean particle number and black carbon concentrations, 2500 particles/cm3 and 149 ng/m3), 1.3 mm Hg for medium exposure (mean particle number and black carbon concentrations, 11 000 particles/cm3 and 409 ng/m3), and 2.8 mm Hg for high exposure (mean particle number and black carbon concentrations, 30 000 particles/cm3 and 826 ng/m3; linear trend P=0.019). There were no statistically significant differences in the secondary outcomes, diastolic BP, or heart rate. In conclusion, reducing indoor concentrations of TRAP was effective in preventing acute increases in SBP.

Compressibility effects in turbulent transport of the temperature field.

Compressibility effects in a turbulent transport of temperature field are investigated by applying the quasilinear approach for small Péclet numbers and the spectral τ approach for large Péclet numbers. The compressibility of a fluid flow reduces the turbulent diffusivity of the mean temperature field similarly to that for the particle number density and magnetic field. However, expressions for the turbulent diffusion coefficient for the mean temperature field in a compressible turbulence are different from those for the mean particle number density and the mean magnetic field. The combined effect of compressibility and inhomogeneity of turbulence causes an increase of the mean temperature in the regions with more intense velocity fluctuations due to a turbulent pumping. Formally, this effect is similar to a phenomenon of compressible turbophoresis found previously [J. Plasma Phys. 84, 735840502 (2018)JPLPBZ0022-377810.1017/S0022377818000983] for noninertial particles or gaseous admixtures. The gradient of the mean fluid pressure results in an additional turbulent pumping of the mean temperature field. The latter effect is similar to the turbulent barodiffusion of particles and gaseous admixtures. The compressibility of a fluid flow also causes a turbulent cooling of the surrounding fluid due to an additional sink term in the equation for the mean temperature field. There is no analog of this effect for particles.

Effects of Y4Zr3O12 addition on the microstructure and mechanical properties of Fe–15Cr–2W-0.35Ti ODS steels

The addition of Zr can hardly transform all Y2O3 into fine Y–Zr–O dispersoids in the ODS steels, and the residual large Y2O3 and ZrO2 deteriorate the mechanical properties. Hereof, Y4Zr3O12 nanoparticles (NPs) were successfully prepared by stearic acid sol-gel method and directly added in the Fe–15Cr–2W-0.35Ti ODS steels. The effects of Y4Zr3O12 addition on the microstructure and mechanical properties of the ODS steels were systematically characterized. The mean particle size and number density of oxide NPs in the Fe–15Cr–2W-0.35Ti-0.6Y4Zr3O12 steel were 7.9 ± 2.9 nm and 1.4 × 1023 m−3, showing a narrower size distribution than the Fe–15Cr–2W-0.5Ti-0.35Y2O3 steel. Both Y2Ti2O7 in Fe–15Cr–2W-0.5Ti-0.35Y2O3 and Y4Zr3O12 in Fe–15Cr–2W-0.35Ti-0.6Y4Zr3O12 shared the coherent interface with the ferrite matrix, (151‾)Y2Ti2O7//(1‾1‾0)α-Fe and (303)Y4Zr3O12//(110)α-Fe, with lattice misfit of 3.99% and 1.66%. As respect to the mechanical properties, substituting Y2O3 with Y4Zr3O12 did not apparently vary the strength of the ODS steel, but did effectively improve the uniform elongation from 12.2% to 15.5%. The improvement of ductility was attributable not only to the formation of homogeneous oxide NPs but also to the strong bonding force of the coherent interface in the Fe–15Cr–2W-0.35Ti-0.6Y4Zr3O12 steel. With the increasing Y4Zr3O12 content from 0.6 to 1.8 wt%, the tensile strength of the ODS steels increased from 1006 MPa to 1168 MPa, and the plastic deformation capacity still maintained a relatively high uniform elongation of 7.2%. Our work demonstrates a new way to obtain homogeneous oxide dispersoids in the ODS steels and improve the mechanical properties.

Hierarchical Structuring of NMC111-Cathode Materials in Lithium-Ion Batteries: An In-Depth Study on the Influence of Primary and Secondary Particle Sizes on Electrochemical Performance

Commercially used LiNi1/3Mn1/3Co1/3O2 (NMC111) in lithium-ion batteries mainly consists of a large-grained nonporous active material powder prepared by coprecipitation. However, nanomaterials are known to have extreme influence on gravimetric energy density and rate performance but are not used at the industrial scale because of their reactivity, low tap density, and diminished volumetric energy density. To overcome these problems, the build-up of hierarchically structured active materials and electrodes consisting of microsized secondary particles with a primary particle scale in the nanometer range is preferable. In this paper, the preparation and detailed characterization of porous hierarchically structured active materials with two different median secondary particle sizes, namely, 9 and 37 μm, and primary particle sizes in the range 300–1200 nm are presented. Electrochemical investigations by means of rate performance tests show that hierarchically structured electrodes provide higher specific capacities than conventional NMC111, and the cell performance can be tuned by adjustment of processing parameters. In particular, electrodes of coarse granules sintered at 850 °C demonstrate more favorable transport parameters because of electrode build-up, that is, the morphology of the system of active material particles in the electrode, and demonstrate superior discharge capacity. Moreover, electrodes of fine granules show an optimal electrochemical performance using NMC powders sintered at 900 °C. For a better understanding of these results, that is, of process-structure–property relationships at both granule and electrode levels, 3D imaging is performed with a subsequent statistical image analysis. Doing so, geometrical microstructure characteristics such as constrictivity quantifying the strength of bottleneck effects and descriptors for the lengths of shortest transportation paths are computed, such as the mean number of particles, which have to be passed, when going from a particle through the active material to the aluminum foil. The latter one is at lowest for coarse-grained electrodes and seems to be a crucial quantity.

Aerosol Inhalation Delivery of Triazavirin in Mice: Outlooks for Advanced Therapy Against Novel Viral Infections.

Under pandemic-caused emergency, evaluation of the potential of existing antiviral drugs for the treatment of COVID-19 is relevant. Triazavirin, an antiviral drug developed in Russia for per-oral administration, is involved in clinical trials against SARS-CoV-2 coronavirus. This virus has affinity to epithelial cells in respiratory tract, so drug delivery directly in lungs may enhance therapeutic effect and reduce side effects for stomach, liver, kidneys. We elaborated ultrasonic method of triazavirin aerosol generation and investigated the inhalation delivery of this drug in mice. Mean particle size and number concentration of aerosol used in inhalation experiments are 560 nm and 4 × 105 cm−3, respectively. Aerosol mass concentration is 1.6 × 10−4 mg/cm3. Inhalation for 20 min in a nose-only chamber resulted in 2 mg/kg body delivered dose and 2.6 μg/mL triazavirin concentration in blood plasma. Elimination rate constant determined in aerosol administration experiments was ke = 0.077 min−1, which agrees with the value measured after intravenous delivery, but per-oral administration resulted in considerably lower apparent elimination rate constant of pseudo-first order, probably due to non-linear dependence of absorption rate on triazavirin concentration in gastrointestinal tract. The bioavailability of triazavirin aerosol is found to be 85%, which is about four times higher than for per-oral administration.

Unitary evolution to a state with a fixed mean number of particles

In the framework of finite-dimensional Fock space models, for a predefined fixed mean number of particles [Formula: see text], it is shown that there is a “large” multidimensional subspace [Formula: see text] of initial pure states, in the space [Formula: see text] of all pure states, unitarily evolving to a subspace [Formula: see text] of final pure states which yield [Formula: see text]. As an example, in particular it follows that the blackbody form of the mean number of particles [Formula: see text] does not by itself contradict unitarity of black hole evaporation.

Asymptotic PN Approximation in Radiative Transfer Problems

We study the validity of the time-dependent asymptotic PN approximation in radiative transfer of photons. The time-dependent asymptotic PN is an approximation which uses the standard PN equations with a closure that is based on the asymptotic solution of the exact Boltzmann equation for a homogeneous problem, in space and time. The asymptotic PN approximation for radiative transfer requires careful treatment regarding the closure equation. Specifically, the mean number of particles that are emitted per collision () can be larger than one due to inner or outer radiation sources and the coefficients of the closure must be extended for these cases. Our approximation is tested against a well-known radiative transfer benchmark. It yields excellent results, with almost correct particle velocity that controls the radiative heat-wave fronts.

Impacts of electronic cigarettes usage on air quality of vape shops and their nearby areas

With the rapid growth of the electronic cigarette (e-cig) market, there is an increasing number of vape shops that exclusively sell e-cigs. The use of e-cigs in the vape shop is a primary source of indoor particles, which might transport to its nearby indoor spaces in the multiunit setting. In this study, six pairs of vape shops and neighboring businesses in Southern California were recruited for real-time measurements of particulate pollutants between February 2017 and October 2019. The mean (SD) particle number concentration (PNC) and PM2.5 concentration in the studied vape shops were 2.8 × 104 (2.3 × 104) particles/cm3 and 276 (546) μg/m3, which were substantially higher than those in neighboring businesses and outdoor areas. In addition, 24-h time-weighted average (TWA) nicotine sampling was conducted in the six pairs and three additional pairs. Nicotine was detected in the air of all the studied vape shops and neighboring businesses, in which the mean (SD) concentration was 2.59 (1.02) and 0.17 (0.13) μg/m3, respectively. Inside vape shops, the dilution-corrected vaping density (puffs/h/100 m3) is a strong predictor of the particle concentration, and nicotine concentration highly depends on the air exchange rate (AER). Out of the six studied pairs, PNCs in five vape shops and PM2.5 in two vape shops were significantly correlated with those in their neighboring businesses. This correlation was stronger when the door of the vape shop was closed. When the door was open, environmental electronic vaping (EEV) aerosols, especially smaller particles, could transport from the vape shop to the outdoor environment. Overall, e-cig usage in the vape shop impacts both its own and nearby air quality, raising concerns regarding the risk of exposure to EEV aerosols in the surrounding environments.

Numerically statistical investigation of the partly super-exponential growth rate in the COVID-19 pandemic (throughout the world)

Abstract A number of particles in a multiplying medium under rather general conditions is asymptotically exponential with respect to time t with the parameter λ, i.e., with the index of power λ ⁢ t {\lambda t} . If the medium is random, then the parameter λ is the random variable. To estimate the temporal asymptotics of the mean particles number (via the medium realizations), it is possible to average the exponential function via the corresponding distribution. Assuming that this distribution is Gaussian, the super-exponential estimate of the mean particle number could be obtained and expressed by the exponent with the index of power t ⁢ E ⁢ λ + t 2 ⁢ D ⁢ λ 2 {t{\rm E}\lambda+t^{2}{\rm D}\frac{\lambda}{2}} . The application of this new formula to investigation of the COVID-19 pandemic is performed.

Particle-number distribution in large fluctuations at the tip of branching random walks.

We investigate properties of the particle distribution near the tip of one-dimensional branching random walks at large times t, focusing on unusual realizations in which the rightmost lead particle is very far ahead of its expected position, but still within a distance smaller than the diffusion radius ∼sqrt[t]. Our approach consists in a study of the generating function G_{Δx}(λ)=∑_{n}λ^{n}p_{n}(Δx) for the probabilities p_{n}(Δx) of observing n particles in an interval of given size Δx from the lead particle to its left, fixing the position of the latter. This generating function can be expressed with the help of functions solving the Fisher-Kolmogorov-Petrovsky-Piscounov (FKPP) equation with suitable initial conditions. In the infinite-time and large-Δx limits, we find that the mean number of particles in the interval grows exponentially with Δx, and that the generating function obeys a nontrivial scaling law, depending on Δx and λ through the combined variable [Δx-f(λ)]^{3}/Δx^{2}, where f(λ)≡-ln(1-λ)-ln[-ln(1-λ)]. From this property, one may conjecture that the growth of the typical particle number with the size of the interval is slower than exponential, but, surprisingly enough, only by a subleading factor at large Δx. The scaling we argue is consistent with results from a numerical integration of the FKPP equation.

Effects of forests on particle number concentrations in near-road environments across three geographic regions

Trees and other vegetation have been advocated as a mitigation measure for urban air pollution mainly due to the fact that they passively filter particles from the air. However, mounting evidence suggests that vegetation may also worsen air quality by slowing the dispersion of pollutants and by producing volatile organic compounds that contribute to formation of ozone and other secondary pollutants. We monitored nanoparticle (>10 nm) counts along distance gradients away from major roads along paired transects across open and forested landscapes in Baltimore (USA), Helsinki (Finland) and Shenyang (China) − i.e. sites in three biomes with different pollution levels − using condensation particle counters. Mean particle number concentrations averaged across all sampling sites were clearly reduced (15%) by the presence of forest cover only in Helsinki. For Baltimore and Shenyang, levels showed no significant difference between the open and forested transects at any of the sampling distances. This suggests that nanoparticle deposition on trees is often counterbalanced by other factors, including differing flow fields and aerosol processes under varying meteorological conditions. Similarly, consistent differences in high frequency data patterns between the transects were detected only in Helsinki. No correlations between nanoparticle concentrations and solar radiation or local wind speed as affecting nanoparticle abundances were found, but they were to some extent associated with canopy closure. These data add to the accumulating evidence according to which trees do not necessarily improve air quality in near-road environments.

Comparison of particulate contamination in glass and plastic ampoules of glycyrrhizin injections after ampoule cutting

We evaluated the number and types of particles in glycyrrhizin injections after ampoule cutting. A total of 100 glass ampoules of 5 companies were examined. The mean number of particles with diameter of 1.3- < 5 μm was 252.9/mL, and that of particles with diameter of 5- < 10 μm was 12.5/mL. The number of particles differed among products of the 5 companies, e.g., the number of particles with a diameter of 1.3- < 5 μm varied from 351.9/mL to 121.6/mL. In addition, a total of 120 plastic ampoules from 6 companies were evaluated. The mean number of particles with a diameter of 1.3- < 5 μm was 43.0/mL, and that of particles with a diameter of 5- <10 μm was 2.1/mL. Differences among products of the 6 companies were not significant. The number of particles in glycyrrhizin injections after ampoule cutting was significantly lower in plastic than for glass ampoules (p < 0.0001). Scanning electron microscopy and X-ray microanalysis identified glass fragments in glycyrrhizin injection samples after the cutting of glass ampoules but identified no particles after cutting plastic ampoules. Glycyrrhizin injections are commonly used in Asia including Japan, Taiwan, and China. The use of plastic ampoules is recommended for the prevention of the entry of glass fragments into the body.

Effect of Electrocautery Settings on Particulate Concentrations in Surgical Plume during Tonsillectomy.

To describe the effect of monopolar electrocautery (EC) settings on surgical plume particulate concentration during pediatric tonsillectomy. Cross-sectional study. Tertiary medical center. During total tonsillectomy exclusively performed with EC, air was sampled with a surgeon-worn portable particle counter. The airborne mean and maximum particle concentrations were compared for tonsillectomy performed with EC at 12 W vs 20 W, with smoke evacuation system (SES) and no smoke evacuation (NS). A total of 36 children were included in this analysis: 9 cases with EC at 12 W and SES (12SES), 9 cases with EC at 20 W and SES (20SES), 9 cases with EC at 12 W without SES (12NS), and 9 cases with EC at 20 W without SES (20NS). Mean particle number concentration in the breathing zone during tonsillectomy was 1661 particles/cm3 for 12SES, 5515 particles/cm3 for 20SES, 8208 particles/cm3 for 12NS, and 78,506 particles/cm3 for 20NS. There was a statistically significant difference in the particle number concentrations among the 4 groups. The correlation between the particle number concentration and EC time was either moderate (for 12SES) or negative (for remaining groups). Airborne particle concentrations during tonsillectomy are over 9.5 times higher when EC is set at 20 W vs 12 W with NS, which is mitigated to 3.3 times with SES. Applying lower EC settings with SES during pediatric tonsillectomy significantly reduces surgical plume exposure for patients, surgeons, and operating room personnel, which is a well-known occupational health hazard.

An analytical solution of the population balance equation for simultaneous Brownian and shear coagulation in the continuum regime

Brownian coagulation of aerosol particles can take place in both laminar and turbulent flows. Thus, the simultaneous Brownian and shear coagulation will always occur in practical applications. This study presents an analytical solution to describe the size evolution of polydisperse particles undergoing simultaneous Brownian and shear coagulation. The analytical solution is derived using the log-normal method of moments (LNMOM) with some approximations. Then, the analytical solution is validated by comparing with previous analytical solutions derived for limiting cases. The results show that the present analytical solution is consistent with previous analytical solutions for these limiting cases. Further, the time trajectories of the total particle number concentration, the geometric standard deviation and the geometric number mean particle volume predicted by the present analytical solution are compared with those of a numerical LNMOM model. The results show that the present analytical solution gives good predictions of the total particle number concentration but less accurate predictions of the geometric standard deviation and the geometric number mean particle volume. A dimensionless analysis shows that the coagulation rate ratio and the initial polydispersity are two important factors for characterizing the size evolution of simultaneous Brownian and shear coagulation.

Comparative analysis of ventilation efficiency on ultrafine particle removal in university MakerSpaces

The proliferation of 3D printing MakerSpaces in university settings has led to an increased risk of student and technician exposure to ultrafine particles. New MakerSpaces do not have standardized specifications to aid in the design of the space; therefore, a need exists to characterize the impacts of different engineering controls on MakerSpace air quality. This study compares three university MakerSpaces: a library MakerSpace operating ≤4 devices under typical office space ventilation with no engineering controls, a laboratory MakerSpace operating 29 printers inside grated cabinets, with laboratory-grade ventilation, and a center MakerSpace operating ≤4 devices with neither engineering controls nor internal ventilation. All MakerSpaces were studied under both controlled (using a standard print design) and uncontrolled (real-time user operation) conditions measuring emitted particle concentrations in the near-field. Additionally, volatile organic emissions and the difference between near-field and far-field particle concentrations were investigated in multiple MakerSpaces. The center MakerSpace had the greatest net increase in mean particle number concentration (+1378.9% relative to background during a print campaign using polylactic acid (PLA) filament in a MakerBot (MakerBot-PLA)). The number-weighted mean diameter had the greatest change relative to background during the library campaign, +37.1% for the Lulzbot-PLA and −56.1% for the Ultimaker-PLA studies. For the standard NIST design with MakerBot-PLA, the laboratory's particle removal ratio was 30 times greater than in the library with open cabinets and 54 times greater when the cabinet doors were closed. The average particle removal rate from the center MakerSpace was up to 2.5 times less efficient than that of the library for the same MakerBot-PLA combination. These results suggest ventilation as a key priority in the design of a new university MakerSpace.

Morphology analysis of soot particles from a modern diesel engine fueled with different types of oxygenated fuels

Using a transmission electron microscopy (TEM), the morphological characteristic variations of exhaust soot particles have been studied on a modern diesel engine fuelled with a commercial diesel fuel (D100, as a baseline fuel) and three different oxygenated fuel blends with the same oxygen content, including a 11.5% methanol blend (M11.5), a 8.3% dimethyl carbonate blend (DMC8.3), and a 13% dimethyl methane blend (DMM13). The results showed that oxygenated fuel blends emitted smaller soot primary particles with respect to neat diesel, with the most significant decrease in M11.5 followed by DMM13 and DMC8.3. Similar variations with primary particle diameter were found in the decrease of the mean radius of gyration, mean primary particle number and estimated mass for an agglomerate when making comparisons among diesel and the three oxygenated fuel blends. Aggregates shape analysis showed that M11.5 soot had the minimal trend to form a rather circular structure and maximal boundary irregularity among the four fuels, while all soot particles showed larger deviation to the sphere (i.e. higher elongation) regardless of fuel type used. In addition, both mass and perimeter fractal dimension showed consistent results for diesel and the three oxygenated fuel blends, with the particle aggregates being the least compacted morphology for M11.5, followed by DMM13, DMC8.3 and diesel. Therefore, compared to diesel, the exhaust soot particles from the oxygenated fuel blends (especially for M11.5) are more prone to be trapped (lowest fractal dimension) and display a higher reactivity towards oxidation (smallest primary particle size).

The role and influence of hydrogeochemistry in the behaviour and fate of silver nanoparticles in freshwater systems

This paper reports on the occurrence, fate and influence of selected hydrogeochemical parameters in the distribution profile of Ag NPs in freshwater from selected dams in South Africa. Single particle-inductively coupled plasma mass spectrometry (SP-ICPMS) was used to characterize, detect, and quantify Ag NPs in aqueous samples. The same technique was applied to determine particle size, particle number concentration and dissolved concentration of Ag NPs in water samples collected from the selected dams. The mean particle number concentration ranged from 6.92 × 103 parts/mL to 1.04 × 105 parts/mL. The mean dissolved Ag ranged from concentration of 0.18 µg/L to 0.27 µg/L, while the size of Ag ranged from 12.52 to 20.01 nm. From this work, it was proved that, SP-ICPMS is an effective technique for detection and characterization of nanoparticles in aqueous environment. Moreover, this study has revealed that hydrogeochemical properties of water as well as dissolved organic carbon (DOC), affect the presence and physical properties of Ag NPs in aqueous environment.

Vacuum instability in a constant inhomogeneous electric field: a new example of exact nonperturbative calculations

Basic quantum processes (such as particle creation, reflection, and transmission on the corresponding Klein steps) caused by inverse-square electric fields are calculated. These results represent a new example of exact nonperturbative calculations in the framework of QED. The inverse-square electric field is time-independent, inhomogeneous in the x -direction, and is inversely proportional to x squared. We find exact solutions of the Dirac and Klein–Gordon equations with such a field and construct corresponding in- and out-states. With the help of these states and using the techniques developed in the framework of QED with x-electric potential steps, we calculate characteristics of the vacuum instability, such as differential and total mean numbers of particles created from the vacuum and vacuum-to-vacuum transition probabilities. We study the vacuum instability for two particular backgrounds: for fields widely stretches over the x-axis (small-gradient configuration) and for the fields sharply concentrates near the origin x=0 (sharp-gradient configuration). We compare exact results with ones calculated numerically. Finally, we consider the electric field configuration, composed by inverse-square fields and by an x-independent electric field between them to study the role of growing and decaying processes in the vacuum instability.

Investigating Soot Parameters in an Ethane/Air Counterflow Diffusion Flame at Elevated Pressures

ABSTRACT Soot emissions from diesel engines and gas turbines are influenced by the combustion environment. Pressure is one of the parameters, which affects particulate emissions, and these effects are poorly understood on soot parameters. In this work, pressurized counterflow diffusion flame of ethane and air has been investigated using two angle light scattering and extinction technique. A counterflow diffusion flame has been stabilized from 2 to 5 atm in a pressure vessel, which can provide optical access from 10 to 165° in angular direction. Global strain rate (a) of 30 s −1 is maintained at all pressures by adjusting the inlet flows. Scattering measurements are performed at two angles (45° and 135°) and Rayleigh-Debye-Gans theory for Fractal Aggregates (RDG-FA) has been used to determine soot parameters from light scattering and extinction data. By combining the scattering at 135° with laser extinction measurements, path averaged soot volume fraction (f v), mean primary particle diameter () and particle number densities (n p), along the axis of the counterflow flame are calculated. Local soot volume fraction (f v,local) profiles are also measured using diffuse light 2D line of sight attenuation technique. Peak value of f v increases from 0.3 to 8 ppm as the pressure is raised from 2 to 5 atm. Primary particle size () also increases with pressure where peak primary particle size of 11 nm at 2 atm rises to 38 nm at 5 atm. Population average radius of gyration (R g) increases with pressure while the number densities (n p) of primary particles decrease due to coalescence.