Search results for "Particle"
showing 10 items of 15225 documents
Atherogenic lipoprotein phenotype and low-density lipoproteins size and subclasses in women with polycystic ovary syndrome.
2006
Abstract Context: An altered lipid profile is common in polycystic ovary syndrome (PCOS) and is usually characterized by increased triglycerides and low high-density lipoprotein (HDL)-cholesterol levels. In the general population, these alterations are often associated with the increase of small low-density lipoproteins (LDLs) in the so-called “atherogenic lipoprotein phenotype” (ALP) that determines a further increase of cardiovascular risk. In this study, we evaluated the presence of ALP in the plasma of women with PCOS. Setting: Measurements and analysis of LDL size were performed at the Clinic of Endocrinology, Diabetes, and Clinical Nutrition, University Hospital, Zurich. PCOS patients…
Targeted Hybrid Nanocarriers as a System Enhancing the Skin Structure
2021
The skin is constantly exposed to external and internal factors that disturb its function. In this work, two nanosystems-levan nanoparticles and a surfactin-stabilized nanoemulsion were preserved (tested for microbial growth) and characterized (size, polydispersity, Zeta potential, and stability). The nanosystems were introduced in the model formulations-cream, tonic, and gel, and confirmed by TEM. The analysis showed that nanoemulsion has a spherical morphology and size 220–300 nm, while levan nanoparticles had irregular shapes independently of the use of matrix and with particle size (130–260 nm). Additionally, we examined the antiradical effect of levan nanoparticles and nanoemulsion in …
Aerosol properties of the Eyjafjallajökull ash derived from sun photometer and satellite observations over the Iberian Peninsula
2012
The Eyjafjallajökull ash that crossed over Spain and Portugal on 6e12 May 2010 has been monitored by a set of operational sun photometer sites within AERONET-RIMA and satellite sensors. The sun photometer observations (aerosol optical depth, coarse mode concentrations) and ash products from IASI and SEVIRI satellite sensors, together with FLEXPART simulations of particle transport, allow identifying the volcanic aerosols. The aerosol columnar properties derived from inversions were investigated, indicating specific properties, especially regarding the absorption. The single scattering albedo was high (0.95 at 440 nm) and nearly wavelength independent, although with slight decrease with wave…
COARSEMAP: synthesis of observations and models for coarse-mode aerosols
2017
Coarse mode aerosols influence Earth's climate and biogeochemistry by interacting with long-wave radiation, promoting ice nucleation, and contributing important elements to biogeochemical cycles during deposition. Yet coarse mode aerosols have received less emphasis in the scientific literature. Here we present first efforts to globally synthesize available mass concentration, compositionand optical depth data and modeling for the coarse mode aerosols (<10 μm) in a new project called "COARSEMAP" (http://www.geo.cornell.edu/eas/PeoplePlaces/Faculty/mahowald/COARSEMAP/). We seek more collaborators who have observational data, especially including elemental or composition data, and/or who a…
High Pressure Inside Nanometer-Sized Particles Influences the Rate and Products of Chemical Reactions
2021
International audience; The composition of organic aerosol has a pivotal influence on aerosol properties such as toxicity and cloud droplet formation capability, which could affect both climate and air quality. However, a comprehensive and fundamental understanding of the chemical and physical processes that occur in nanometer-sized atmospheric particles remains a challenge that severely limits the quantification and predictive capabilities of aerosol formation pathways. Here, we investigated the effects of a fundamental and hitherto unconsidered physical property of nanoparticles-the Laplace pressure. By studying the reaction of glyoxal with ammonium sulfate, both ubiquitous and important …
Force control and powder dispersibility of spray dried particles for inhalation
2009
This study aims towards a deeper understanding of the correlation between particle morphology, cohesion forces, and aerosol performance of spray dried powders for inhalation. Therefore, forces affecting cohesion and dispersion are consid- ered and some novel contact models are introduced to explain the improved powder dispersibility of corrugated particles. Particles with different degrees of corrugation are prepared by spray drying and characterized. Powder dispersibility is measured by positioning a dry powder inhaler in front of the laser diffraction device. The particle sizes of all powders are in the range of x50 ¼ 2.11 � 0.15 mm. The ratio of mass specific surface area Sm to volume sp…
Effective broadband refractive index retrieval by a white light optical particle counter.
2009
A new approach to retrieve the effective broadband refractive indices (nbroad,eff) of aerosol particles by a white light aerosol spectrometer (WELAS) optical particle counter (OPC) is presented. Using a tandem differential mobility analyzer (DMA)-OPC system, the nbroad,eff are obtained for both laboratory and field applications. This method was tested in the laboratory using substances with a wide range of optical properties. With the obtained nbroad,eff, WELAS aerosol size distributions can be corrected. Therefore, this method can be used for instrument calibration in both laboratory and field measurements. The retrieved effective broadband refractive indices for the scattering aerosols we…
Application of time-of-flight aerosol mass spectrometry for the online measurement of gaseous molecular iodine.
2012
Here we present a new application of a time-of-flight aerosol mass spectrometer (TOF-AMS) for the measurement of atmospheric trace gases in real-time. Usually, TOF-AMS instruments are not sensitive to gas-phase species due to the aerodynamic particle focusing inlet system which reduces the gas phase species by a factor of about 10(7) relative to the particle phase. This efficient removal of the gas phase and the resulting high relative enrichment of particles is one reason for the very high sensitivity of TOF-AMS instruments for particle phase compounds (detection limits in the sub-μg/m(3)-range for online measurements with 1 min integration time), which allows application of the instrument…
SW—Soil and Water
2002
Abstract Recent research has directed attention to the size distribution of eroded material because of its influence on deposition mechanics and in carrying capacity of pollutant materials. At first, in this paper the relationship between aggregate breakdown mechanism and erosion processes is briefly reviewed. Then the link between the clay enrichment ratio and the sediment delivery ratio at morphological unit scale is investigated. For 129 soil samples well distributed over the Sicilian Sparacia basin, the values for the experimental clay enrichment ratio calculated by the measured ultimate grain-size distributions are compared with the theoretical clay enrichment ratio values obtained by …
Self-assembly of colloidal micelles in microfluidic channels.
2016
The self-assembly of amphiphilic Janus colloids in microfluidic channels is studied using hybrid molecular dynamics simulations with fully resolved hydrodynamic interactions incorporated through the multi-particle collision dynamics algorithm. The simulations are conducted at a density and temperature where the Janus particles spontaneously self-assemble into spherical micelles to minimize the interface between the solvophobic caps and the surrounding solvent. In confined systems, this contact area can also be reduced by aggregation at the channel walls. Indeed, a sizable fraction of free particles and small clusters with three and four members are found at the walls when the microfluidic c…