Fraction Profiles Research Articles

Mixed convective flow of nanofluid across exponential surface: A numerical assessment of the impact of Darcy-Forchheimer and nanoparticle aggregation

Improving heat transmission is a modern difficulty faced in a multitude of areas, incorporating but not limited to electronics, heat exchangers, biochemical reactors, and other similar areas. In their capacity as cutting-edge heat transfer fluids, nanofluids have the promise of becoming a useful instrument in the pursuit of greater energy transfer efficiency. So, the focus of this work is on how it is possible to enhance heat transmission by using nanofluids. Using a stretched exponentially accelerating surface, this analysis investigates the effect that nanoparticle aggregation with thermal radiation has on the nanofluid of mixed convective stagnation point flow through Darcy-Forchheimer porous surfaces. The aggregation of nanoparticles may be assessed using modified Krieger-Dougherty and Maxwell-Bruggeman models. By using the right similarity transformations, the controlling equations of this problem were turned into a numerical model that can be unraveled. Mathematica was used to resolve the issue numerically by using the shooting with Runge-Kutta (RK-IV) procedure. nanoparticles with base fluid under aggregation effect boost heat transfer performance. A diversity of parameter estimates, including the mixed convection, mass suction, solid volume fraction of nanoparticles, thermal radiation, and stretching, were used to provide solutions for heat transfer and lower skin friction coefficients, as well as velocity and temperature curves. In addition to the findings, there were graphs and tables with explanations. The increase in heat transfer rates was 6.7021% when the suction parameters were set between 2.0 to 2.5 with =0.01. When the amount of nanoparticles volume fraction went from 0% to 1% by volume, the ineptitude of heat transfer went by an average of 4.249%. Aggregation models are often favored over non-aggregation models due to their ability to provide more accurate velocity and skin fraction profiles. Because of their superior precision, they are often used in situations where accuracy is paramount.

Unraveling the mechanisms of Fenugreek seed for managing different gynecological disorders: steroidal saponins and isoflavones revealed as key bioactive metabolites

This study employed network pharmacology-based analysis and reverse molecular docking to investigate the molecular targets and pathways associated with gynecological disorders, particularly those related to steroidal hormones and their receptors, and the potential therapeutic effects of fenugreek (Trigonella foenum-graecum L.) constituents. The STITCH 5.0 database was utilized to identify potential molecular targets, and a compound-target network was constructed. The main targets associated with gynecological disorders included estrogen receptor beta (ESR2), estrogen-related receptor gamma (GPER1), oxytocin receptor (OXTR), progesterone receptor (PGR), prolactin receptor (PRLR), and several enzymes involved in sex hormone biosynthesis. Additionally, network topological analysis revealed that specific compounds, such as quercetin, luteolin, genistein, and vitexin, had significant interactions with the identified targets. Reverse molecular docking analysis confirmed the interactions between the identified compounds and target proteins where quercetin, luteolin, genistein, 4'-methylgenistein, trigoneoside IIB, diosgenin, and vitexin possessed the highest combined docking scores, indicating their multi-target nature. The results highlighted the potential of steroidal saponins, isoflavones, and flavones as active constituents of fenugreek with implications for lactation, reproductive processes, and estrogenic activity. The chemical profiling of saponin-enriched and flavonoid-enriched fractions using UPLC/MS/MS further supported the presence of these bioactive compounds. In an animal model study, the steroidal saponins-enriched fraction of fenugreek seed exhibited a significant increase in the body weight of lactating female rats and serum prolactin levels while the flavonoids-enriched fraction showed an increase in serum estradiol levels and improved the histological structure of ovaries.

Tsantan Sumtang, a traditional Tibetan medicine, protects pulmonary vascular endothelial function of hypoxia-induced pulmonary hypertension rats through AKT/eNOS signaling pathway

Ethnopharmacological relevanceTsantan Sumtang (TS), originated from the Four Tantras, is an empirical Tibetan medicine prescription, which has been widely used for treating cardiovascular diseases in the clinic in Qinghai Province of China. Our previous studies found that TS alleviated hypoxia-induced pulmonary hypertension (HPH) in rats. However, the effect and bioactive fractions of TS on hypoxia-injured pulmonary vascular endothelium are unknown. Aim of the studyTo investigate the effect, bioactive fractions and pharmacological mechanism of TS on hypoxia-injured pulmonary vascular endothelium in vivo and in vitro. Materials and methodsIn vivo studies, HPH animal model was established, and TS was administrated for four weeks. Then, hemodynamic indexes, ex vivo pulmonary artery perfusion experiment, morphological characteristics, nitric oxide (NO) production, and the protein expression of protein kinase B (AKT)/endothelial nitric oxide synthase (eNOS) and AMP-activated protein kinase (AMPK)/eNOS signaling were determined. In vitro studies, 1% O2-induced pulmonary artery endothelial cells (PAECs) injury model was applied for screening bioactive fractions of TS by cell proliferation assay and NO production measurement. The associated proteins of AKT/eNOS signaling were further measured to elucidate underlying mechanism of bioactive fraction of TS via using phosphatidylinositol-3 kinase (PI3K) inhibitor LY294002. Ultra-high performance liquid chromatography with hybrid quadrupole-orbitrap mass spectrometry (UHPLC-Q-Exactive Orbitrap-MS) was used to reveal the chemical profile of bioactive fraction of TS. ResultsTS showed protective effect on the integrity of distal pulmonary arterial endothelium in HPH rats. Tsantan Sumtang dilated pulmonary arterial rings in HPH rats. TS enhanced NO bioavailability in lung tissue via regulating AKT/eNOS signaling. Furthermore, in the cellular level, cell viability as well as NO content of hypoxia-injured PAECs were elevated by fraction 17 of water extract of TS (WTS), through activating the AKT/eNOS signaling. Ellagic acid could be one of compositions in fraction 17 of WTS to produce NO in hypoxia-injured PAECs. ConclusionTS restored pulmonary arterial endothelial function in HPH rats. The bioactive fraction 17 was screened, which protected hypoxia-injured PAECs via upregulating AKT/eNOS signaling.

Toward Renewable-Based Prebiotics from Woody Biomass: Potential of Tailored Xylo-Oligosaccharides Obtained by Enzymatic Hydrolysis of Beechwood Xylan as a Prebiotic Feed Supplement for Young Broilers.

Although antibiotic resistance emerges naturally, this process has been accelerated by the worldwide overuse and misuse of antibiotics. It is essential to find effective alternatives in the broiler industry to improve poultry health while maintaining production efficiency and product safety. In this study, we aimed to evaluate a potential alternative: wood-derived xylo-oligosaccharides (XOS). The objective of this research was to investigate the potential of XOS prepared using enzymatic hydrolysis of beechwood xylan as a prebiotic feed supplement for broilers. A pilot study was conducted to explore the optimal XOS fraction profile by in vitro fermentation. Subsequently, a semi-continuous enzyme membrane reactor was used, allowing for the production of tailored XOS in large quantities. Given the strong bidirectional relationship between intestinal health, nutrition, and intestinal microbiota composition in broilers, an in vivo experiment was performed to explore the potential of XOS as a prebiotic feed supplement by investigating growth performance, feed conversion ratio, caecal short and medium chain fatty acid (SCFA and MCFA) concentration, and microbiological composition of the caecal content. Results from the pilot study indicated that higher enzyme concentrations in the hydrolysis process yield a product that leads to a higher total SCFA and MCFA- and butyric acid production during in vitro fermentation by caecal bacteria. Supplementation of the tailored XOS to the broiler diet (day 1 (d1)-d8 0.13% wt/wt XOS, d9-d15 0.32% XOS) resulted in higher Bifidobacterium counts, beneficial to the health of birds, on d11 and d15.

Euler-Euler LES of bubble column bubbly flows by considering sub-grid scale turbulent dispersion effect on modulating bubble transport

It has now been recognised and generally accepted that turbulent dispersion may be modelled using the time average of the fluctuating part of the interphase momentum, employing the drag the Favre averaged drag model for turbulent dispersion in Eulerian multi-phase flows. As the turbulent eddies in the surrounding of bubbles interact strongly with the bubbles in bubbly flow, the bubble trajectories and bubble oscillation take place accordingly as the consequence of continuous deformation of the bubble surfaces. When using large eddy simulation for modelling bubbly flow, the sub-grid scale (SGS) filtered velocity fluctuations of liquid phase can be interpreted as many small eddies that may act on the surface of bubbles, consequently giving rise to bubble shape variations and the dispersion of bubbles. This study employs Euler/Euler large-eddy simulation (LES) modelling to demonstrate that the turbulent dispersion force model can be used to effectively indicate the influence of turbulent eddies on bubble dynamics, in particular the bubble cluster oscillations, which leads to remarkable improvements in the prediction of bubble lateral dispersion behaviour. The use of spatial filtering to model the SGS bubble dispersion is proposed with a modification on SGS eddy viscosity to reflect turbulent dispersion due to bubble induced turbulence. The results of the time-averaged LES modelled bubble velocities and bubble volume fraction profiles are in good agreement with the experimental data while the turbulent kinetic energy spectrum obtained at different locations on the centreline of the bubble column still exhibits the conventional −5/3 scaling for shear induced turbulence and a −3 scaling for bubble induced turbulence.

Studying the variability of fluorescence emission and the presence of clumpy wind in HMXB GX 301−2 using XMM–Newton

ABSTRACT We present the results from an analysis of data from an XMM–Newton observation of the accreting high-mass X-ray binary pulsar GX 301−2. Spectral analysis in the non-flaring segment of the observation revealed that the equivalent width of the iron fluorescence emission is correlated with the observed absorption column density and the ratio of the iron Kβ and Kα line strength varied with the flux of the source. Coherent pulsations were detected with the spin period of the pulsar of 687.9 ± 0.1 s, and a secondary pulsation was also detected with a period of 671.8 ± 0.2 s, most prominent in the energy band of the iron line. At the spin period of the neutron star, the pulsation of the iron line has a low amplitude and the profile is different from the continuum. Pulse phase-resolved spectroscopy also revealed pulsations of the iron emission line during the non-flaring segment of the light curve. At the secondary period, both the iron line and the continuum have nearly identical pulse fraction and pulse profile. The additional periodicity can be attributed to the beat frequency between the spin of the neutron star and the Keplerian frequency of a stellar wind clump in retrograde motion around the neutron star. Reprocessed X-ray emissions originating from the clump can produce the observed secondary pulsations both in the continuum and the iron fluorescence line. The clump rotating around the neutron star is estimated to be approximately five lt-s away from the neutron star.

Nonlinear effect of grain elongation on the flow rate in silo discharge.

By means of two-dimensional numerical simulations based on contact dynamics, we present a systematic analysis of the joint effects of grain shape (i.e., grain elongation) and system size on silo discharge for increasing orifice sizes D. Grains are rounded-cap rectangles whose aspect ratio are varied from 1 (disks) to 7. In order to clearly isolate the effect of grain shape, the mass of the grains is keeping constant as well as the condition of the discharge by reintroducing the exiting grains at the top of the silo. In order to quantify the possible size effects, the thickness W of the silos is varied from 7 to 70 grains diameter, while keeping the silos aspect ratio always equal to 2. We find that, as long as size effects are negligible, the flow rate Q increases as a Beverloo-like function with D, also for the most elongated grains. In contrast, the effects of grain elongation on the flow rate depend on orifice size. For small normalized orifice sizes, the flow rate is nearly independent with grain elongation. For intermediate normalized orifice sizes the flow rate first increases with grain elongation up to a maximum value that depends on the normalized size of the orifice and saturates as the grains become more elongated. For larger normalized orifice size, the flow rate is an increasing function of grains' aspect ratio. Velocity profiles and packing fraction profiles close to the orifice turn out to be self-similar for all grain shapes and for the whole range of orifice and system sizes studied. Following the methodology introduced by Janda etal. [Phys. Rev. Lett. 108, 248001 (2012)PRLTAO0031-900710.1103/PhysRevLett.108.248001], we explain the nonlinear variation of Q with grain elongation, and for all orifice sizes, from compensation mechanisms between the velocity and packing fraction measured at the center of the orifice. Finally, an equationto predict the evolution of Q as a function of the aspect ratio of the grains is deduced.

Study of demixing in C–F plasma produced in a capillary discharge

The spatial distribution of chemical elements in plasma produced by a pulsed discharge in a capillary made of polytetrafluoroethylene has been studied by methods and means of optical spectroscopy. It has been found that the ratio of the molar fractions of fluorine and carbon differs significantly from that in the polymer wall and varies nonmonotonically along the radius of the plasma jet emerging from the capillary. The performed qualitative analysis of the intensity and direction of a number of competing diffusion fluxes involving C, C+, F, and F+ indicates both the possibility of the slowdown in the fluorine and carbon demixing, which start from the peripheral zone, and a change in the direction of some of these fluxes in the central zone of the discharge, which is reflected in the measured mole fraction profiles of these elements.

Experimental validation of the mechanism and condition for the onset of significant void in subcooled flow boiling

In evaluating the axial void fraction profile in the subcooled boiling region in heated channels, accurate determination of the point of onset of significant void (POSV) is of critical importance. Recently, it has been reported that the POSV can be predicted with high accuracy if the onset of significant void (OSV) is assumed to be caused by a sudden decrease in the interfacial area due to global bubble coalescence (GBC) leading to the formation of large bubbles. Therefore, in this work, experimental investigations were carried out to measure the void fraction, bubble size and bubble number density. The experimental results were utilized to validate the mechanism causing the OSV in subcooled flow boiling. The experimental results were in qualitative and quantitative agreement with the model based on the GBC concept. Thus, it was validated that the sudden decrease in condensation rate due to large bubble formation is the main cause of OSV. It was also confirmed that the GBC occurs when the local void fraction near the heated wall reaches about 0.3, analogous to the flow regime transition from bubbly flow to slug flow in adiabatic gas-liquid two-phase flows.

The X-ray invisible Universe. A look into the haloes undetected by eROSITA

ABSTRACT The paper presents the analysis of optically selected GAMA groups and clusters in the SRG/eROSITA X-ray map of eROSITA Final Equatorial Depth Survey, in the halo mass range 1013−5 × 1014 M⊙ and at z < 0.2. All X-ray detections have a clear GAMA counterpart, but most of the GAMA groups in the halo mass range 1013−1014 M⊙ remain undetected. We compare the X-ray surface brightness profiles of the eROSITA detected groups with the mean stacked profile of the undetected low-mass haloes at fixed halo mass. Overall, we find that the undetected groups exhibit less concentrated X-ray surface brightness, dark matter, and galaxy distributions with respect to the X-ray-detected haloes. The mean gas mass fraction profiles are consistent in the two samples within 1.5σ, indicating that the gas follows the dark matter profile. The low-mass concentration and the magnitude gap indicate that these systems are young. They reside with a higher probability in filaments while X-ray-detected groups favour the nodes of the Cosmic Web. Because of the lower central emission, the undetected systems tend to be X-ray underluminous at fixed halo mass and to lie below the LX−Mhalo relation. Interestingly, the X-ray-detected systems inhabiting the nodes scatter the less around the relation, while those in filaments tend to lie below it. We do not observe any strong relationship between the system X-ray appearance and the active galactic nucleus (AGN) activity. We cannot exclude the role of the past AGN feedback in affecting the gas distribution over the halo lifetime. However, the data suggests that the observed differences might be related to the halo assembly bias.

Chemical constituents from Mytilaria laosensis Lec. leaves and branches

Phytochemical investigations on the leaves and branches of Mytilaria laosensis Lec. led to the isolation of eight compounds, including four ecdysteroids (1-4), three flavonoids (5–7), and one phenylpropanoid (8). The identification of isolated compounds was achieved on the basis of NMR data, mass spectral data, and comparison with previous literature data. These eight compounds were isolated from M. laosensis for the first time. In addition, compounds 1–4 and 8 were found for the first time in the Hamamelidaceae family. Furthermore, the metabolite profiling of ethyl acetate and n-butanol fractions of M. laosensis were also measured by using liquid chromatography coupled with ion trap and time of flight mass spectrometry (LCMS-IT-TOF). The results of LCMS-IT-TOF analysis showed that this plant has other ecdysteroids and glycosides besides the eight isolated constituents. The chemotaxonomic significance of these compounds was discussed.

Vapor Cloud Behavior of Heavier-Than-Air Hydrocarbon Liquid Evaporating From a Microliter Volume Heated Well Cavity

Abstract Detailed characterization of the vapor cloud above a well or reservoir is not available in literature irrespective of its several practical importance. This study aims to understand the vapor cloud characteristics and vapor phase transport of a heavier-than-air vapor cloud evaporating from a heated microliter circular reservoir. Evaporation of a heavy hydrocarbon (cyclohexane) and a comparatively lighter fluid (ethanol) is studied. Digital holographic interferometry has been used for the characterization of vapor cloud. Gravimetric analysis is used for measurement of evaporation rate from the reservoir. A flat disk-shaped vapor cloud is observed in both heated and nonheated reservoir cases. This is attributed to the presence of radial outward natural convection. The evaporation rate is underpredicted by the diffusion model at a higher Grashof number, i.e., for well heating. Solutal convection dominates near the interface region and thermal convection effect increases in the region away from the liquid–vapor interface. The mole fraction profile depends on the relative strength of the thermal and solutal Grashof number. Thermal convection effect is stronger in lighter vapor of ethanol compared to that of cyclohexane. Overall, this study shows dominance of solutal convection on the vapor cloud characteristics above both heated and unheated reservoir.

Analytical assessment of heat transfer due to Williamson hybrid nanofluid (MoS2 + ZnO) with engine oil base material due to stretched sheet

The efficiency of fuel consumptions and improved performances is real challenge in the vehicle engines. Recent advances in thermal engineering suggested various tools to improve the capacitance of engine oil for which the interaction of nanoparticles is more dynamical. The aim of current research is to enhance the thermal aspects of engine oil with suspension of Williamson hybrid nanofluid. The hybrid nanofluid is the suspension of molybdenum disulfide MoS2 and zinc oxide ZnO. In order to increase the heating capability of system, external heat source and viscous dissipation features are contributed. The flow analysis is based on moving surface contains porous medium. After modelling the problem, the analytical outcomes of attributed with variational iteration method (VIM). The computational simulations are performed with help of Lagrange Multiplier technique. The impact of numerous physical parameters on skin fraction, Nusselt numbers, temperature distribution and velocity profile is exhibited.

Immune profile of adipose tissue from youth with obesity and asthma.

Obesity is a risk factor for paediatric asthma. Obesity-mediated systemic inflammation correlates with metabolic dysregulation; both are associated with asthma burden. However, adipose tissue inflammation is not defined in obesity-related asthma. Define adipose tissue inflammation and its association with metabolic measures in paediatric obesity-related asthma. Cellular profile of stromal vascular fraction from visceral adipose tissue (VAT) from youth with obesity-related asthma (n = 14) and obesity without asthma (n = 23) was analyzed using flow cytometry and correlated with metabolic measures. Compared to youth without asthma, VAT from youth with obesity-related asthma was enriched for leukocytes and macrophages, including M1 and dual M1M2 cells, but did not differ for CD4+ lymphocytes, and endothelial cells, their progenitors, and preadipocytes. M1 macrophage counts positively correlated with glucose, while M1M2 cells, CD4+ lymphocytes, and their subsets negatively correlated with high-density lipoprotein, in youth with obesity without asthma, but not among those with obesity-related asthma. Enrichment of macrophage-mediated inflammation in VAT from youth with obesity-related asthma supports its role in systemic inflammation linked with asthma morbidity. Lack of correlation of VAT cells with metabolic dysregulation in youth with obesity-related asthma identifies a need to define distinguishing factors associated with VAT inflammation in obesity-related asthma.

Role of short germination and milling on physical properties, amino acid and metabolomic profiles of high amylose rice fractions

Short germination is a process that can improve bioactive compounds in rice. This work aimed investigate the physical properties, phenolic compounds (PC), antioxidant activity and amino acids composition of husk + bran, brown and milled rice with high amylose content after short germination (16 h). α-amylase activity (Falling Number, FN) and enthalpy (ΔH) were unchanged (p < 0.05). RVA curve profiles were similar, even though after short germination and milling. Globally, metabolomics analysis identified 117 PC, in which 111 (bound), 104 (free) and 21 revealed in both extracts. p-Coumaric, trans-ferulic and ferulic acids were the most abundant PC revealed in all fractions. The portion husk + bran showed the highest level of total antioxidant activity (709.90 µmol TE) in both free and bound fractions. In terms of total amino acids, there was no statistical difference (p < 0.05) among non-germinated and germinated samples, contrary to free amino acids content. Glutamic acid (Glu) presented the highest values combining short germination and milling (1725–1900 mg/100 g) consequently, leads to higher value of GABA (12.21 mg/100 g). The combination of short germination and milling demonstrated a good strategy to improve the nutritional quality of rice, unless the thermal and pasting properties have been altered, contribute to potential health benefits on human nutrition.

Proteomic Approach to Investigating Expression, Localization, and Functions of the SOWAHD Gene Protein Product during Granulocytic Differentiation.

Cataloging human proteins and evaluation of their expression, cellular localization, functions, and potential medical significance are important tasks for the global proteomic community. At present, localization and functions of protein products for almost half of protein-coding genes remain unknown or poorly understood. Investigation of organelle proteomes is a promising approach to uncovering localization and functions of human proteins. Nuclear proteome is of particular interest because many nuclear proteins, e.g., transcription factors, regulate functions that determine cell fate. Meta-analysis of the nuclear proteome, or nucleome, of HL-60 cells treated with all-trans-retinoic acid (ATRA) has shown that the functions and localization of a protein product of the SOWAHD gene are poorly understood. Also, there is no comprehensive information on the SOWAHD gene expression at the protein level. In HL-60 cells, the number of mRNA transcripts of the SOWAHD gene was determined as 6.4 ± 0.7 transcripts per million molecules. Using targeted mass spectrometry, the content of the SOWAHD protein was measured as 0.27 to 1.25 fmol/μg total protein. The half-life for the protein product of the SOWAHD gene determined using stable isotope pulse-chase labeling was ~19 h. Proteomic profiling of the nuclear fraction of HL-60 cells showed that the content of the SOWAHD protein increased during the ATRA-induced granulocytic differentiation, reached the peak value at 9 h after ATRA addition, and then decreased. Nuclear location and involvement of the SOWAHD protein in the ATRA-induced granulocytic differentiation have been demonstrated for the first time.

An iterative methodology for REDIM reduced chemistry generation and its validation for partially-premixed combustion

Partially-premixed flames (PPFs) incorporate effects of both premixed and non-premixed types of reaction zones. The modelling of PPFs using manifold-based model reduction methods faces some inherent difficulties due to the underlying assumptions of a-priori identification of the type of combustion system. In this work, the reaction–diffusion manifold (REDIM) model reduction method is applied to study PPFs. The REDIM method requires minimal prior knowledge about the type of combustion system, which makes it a suitable method for studying PPFs. It allows incorporating system-specific diffusion (gradients) terms in a generic way so that the manifold can evolve according to the diffusion related information provided by the combustion system. In this way, a prior identification of the type of combustion system is no longer needed. This work utilises an iterative methodology to generate REDIM chemistry tables so that the reduced manifold can be iteratively converged very close to the detailed manifold according to the gradients of the reduced coordinates provided by the physical combustion system in each iteration step. In addition, a new method is proposed to provide the gradient estimates of the reduced coordinates during the generation of REDIM from the scattered gradient data in REDIM reduced CFD calculations. Laminar triple flames, a special case of PPFs, with two types of mixture fraction gradients are selected as the target cases to assess the presented iterative methodology. REDIM reduced calculations are compared with simulations based on detailed finite-rate kinetics. It is found that in the final iteration steps, temperature and all considered major and minor species mass fraction profiles are very well predicted by the REDIM reduced calculations.

Structure of Low Stretched Non-Premixed Counterflow Flames Stabilized in Planar Channel: Mass Spectrometric Study and Numerical Simulation

ABSTRACT In this paper, a methodology for experimental investigation of chemical and thermal structure of weakly stretched counterflow flames under terrestrial conditions is proposed. The non-premixed counterflow flames are stabilized in a narrow channel between quartz plates, and the flame gases are sampled by a microprobe inserted via a thin slit in one of the quartz plates. The gas samples are then analyzed by mass spectrometry. The results of the measurements of mole fraction profiles of the main components of methane-air non-premixed flames, namely, CH4, O2, H2O, CO2, and CO, are presented. The temperature profiles are also reconstructed using the measurement data for the gas composition. The experimental profiles are compared to the results of the 3D numerical simulations undertaken within the global reaction mechanisms (one- and four-step) and a detailed reaction mechanism (San-Diego). The results of this work clearly show that the thermal and chemical structures of the counterflow flame in the planar channel are essentially non-one-dimensional, and 3D-calculations are necessary to correctly predict the flame behavior in this configuration. The methodology demonstrated in the current work can be successfully employed for the investigation of the low stretched counterflow flames of various hydrocarbon fuels and fuel blends. This will allow verifying and developing the reaction kinetic models capable of quantitative prediction of weakly stretched flame behavior in confined conditions.

Assessing Arctic low-level clouds and precipitation from above – a radar perspective

Abstract. Most Arctic clouds occur below 2 km altitude, as revealed by CloudSat satellite observations. However, recent studies suggest that the relatively coarse spatial resolution, low sensitivity, and blind zone of the radar installed on CloudSat may not enable it to comprehensively document low-level clouds. We investigate the impact of these limitations on the Arctic low-level cloud fraction, which is the number of cloudy points with respect to all points as a function of height, derived from CloudSat radar observations. For this purpose, we leverage highly resolved vertical profiles of low-level cloud fraction derived from down-looking Microwave Radar/radiometer for Arctic Clouds (MiRAC) radar reflectivity measurements. MiRAC was operated during four aircraft campaigns that took place in the vicinity of Svalbard during different times of the year, covering more than 25 000 km. This allows us to study the dependence of CloudSat limitations on different synoptic and surface conditions. A forward simulator converts MiRAC measurements to synthetic CloudSat radar reflectivities. These forward simulations are compared with the original CloudSat observations for four satellite underflights to prove the suitability of our forward-simulation approach. Above CloudSat's blind zone of 1 km and below 2.5 km, the forward simulations reveal that CloudSat would overestimate the MiRAC cloud fraction over all campaigns by about 6 percentage points (pp) due to its horizontal resolution and by 12 pp due to its range resolution and underestimate it by 10 pp due to its sensitivity. Especially during cold-air outbreaks over open water, high-reflectivity clouds appear below 1.5 km, which are stretched by CloudSat's pulse length causing the forward-simulated cloud fraction to be 16 pp higher than that observed by MiRAC. The pulse length merges multilayer clouds, whereas thin low-reflectivity clouds remain undetected. Consequently, 48 % of clouds observed by MiRAC belong to multilayer clouds, which reduces by a factor of 4 for the forward-simulated CloudSat counterpart. Despite the overestimation between 1 and 2.5 km, the overall low-level cloud fraction is strongly reduced due to CloudSat's blind zone that misses a cloud fraction of 32 % and half of the total (mainly light) precipitation amount.

Paper spray mass spectrometry profiling of olive oil unsaponifiable fraction for commercial categories classification

A new method for a fast molecular profiling of olive oil unsaponifiable fraction has been developed. This approach, based on paper spray mass spectrometry, allows obtaining MS data with only a few minutes of analysis and without significant solvent and disposable consumption. Tandem mass spectrometry and high-resolution mass spectrometry experiments have been performed to identify the main ions detected. The MS data coming from the analyses of sixty-three samples of three different olive oil categories: extra virgin olive oil (EVOO), virgin olive oil (VOO), and pomace olive oil (POO), have been used to test the discriminative potential. Both unsupervised (PCA and HCA) and supervised (kNN and LDA) chemometric procedures have been applied with good results in prediction. The same approach was tested using direct infusion mass spectrometry data to confirm the ability of paper spray fingerprinting to classify different olive oils correctly.