Search results for "Particle size"
showing 10 items of 631 documents
Atherogenic lipoprotein phenotype and LDL size and subclasses in patients with peripheral arterial disease
2006
The type of dyslipidemia in patients with peripheral arterial disease (PAD) is still ill defined. PAD patients often show elevated triglycerides and reduced HDL-cholesterol, two lipid abnormalities usually accompanied by decreased LDL size in the "atherogenic lipoprotein phenotype" (ALP). We investigated (1) whether PAD patients have lower LDL size, (2) altered LDL subclass distribution and (3) the prevalence of ALP. We measured plasma lipids and LDL size and subclasses by gradient gel electrophoresis in 31 adults with intermittent claudication and 31 age-BMI-matched controls. Patients had higher prevalence of hypertension (p = .0132), smoking (p < .0020) and diabetes (p = .0024), with lowe…
Self-assembled PAA-based nanoparticles as potential gene and protein delivery systems
2012
A series of nanoparticles is prepared via layer-by-layer assembly of oppositely charged, synthetic biocompatible polyamidoamine polymers as potential carriers. Particle size, surface charge and internal chain mobility are quantified as a function of the polymer type and number of layers. The effect of addition of surfactant is examined to simulate the effects of nanoparticle dissolution. The cyctotoxicity of these particles (in epithelia and murine cell lines) are orders of magnitude lower than polyethyleneimine controls. Stable nanoparticles may be prepared from mixtures of strongly, oppositely charged polymers, but less successfully from weakly charged polymers, and, given their acceptabl…
Structural and luminescence properties of amorphous SiO2 nanoparticles
2011
We report an experimental study on the photoluminescence band peaked at 2.7 eV (blue band) induced by thermal treatments in nanometric amorphous SiO 2. In particular the emission dependence on the nanometric particles size as a function of their mean diameter from 7 nm up to 40 nm is investigated. We found that the emission amplitude increases on decreasing the particle diameter, showing a strong correlation between the blue band and the nanometric nature of the particles. By Raman spectroscopy measurements it is evidenced that the SiO2 nanoparticles matrix is significantly affected by the reduction of size. Basing on the shell-like model, these findings are interpreted assuming that the de…
Aerosol filtration efficiency of household materials for homemade face masks: Influence of material properties, particle size, particle electrical ch…
2020
As a consequence of the COVID-19 pandemic caused by the SARS-CoV-2 virus, the widespread daily use of face masks is promoted worldwide. Particle-size dependent filtration efficiencies (FE; dp = 30 nm–10 µm), applying a particle counting approach, and additionally pressure drops (Δp) were determined for 44 samples of household materials and several medical masks. Huge FE differences were found between sample materials and for different particle sizes, spanning from <10% up to almost 100%. Minimum FE were determined for dp = 50–500 nm particles with significantly larger values for dp = 30 nm particles and especially for those with dp > 2.5 µm. Measurements at different numbers of layers…
Dynamic Tuning of Viscoelastic Hydrogels with Carbonyl Iron Microparticles Reveals the Rapid Response of Cells to Three-Dimensional Substrate Mechani…
2021
Current methods to dynamically tune three-dimensional hydrogel mechanics require specific chemistries and substrates that make modest, slow, and often irreversible changes to their mechanical properties, exclude the use of protein-based scaffolds, or alter hydrogel microstructure and pore size. Here, we rapidly and reversibly alter the mechanical properties of hydrogels consisting of extracellular matrix proteins and proteoglycans by adding carbonyl iron microparticles (MP) and applying external magnetic fields. This approach drastically alters hydrogel mechanics: rheology reveals that application of a 4,000 Oe magnetic field to a 5 mg/mL collagen hydrogel containing 10 wt% MPs increases th…
Hydrothermal liquefaction of wood using a modified multistage shrinking-core model
2020
Abstract Wood liquefaction in hot compressed water is modeled using the hydrolysis of Cellulose, Hemicellulose, and Lignin. These three components are reacted under catalyst-free subcritical conditions in a temperature range from 553 K to 640 K, and the heating rate ranges from 2 K/min to 6 K/min. Using a simplified reaction scheme, water-soluble products 1 (WSP), Biocrude, char, and gas are generated through intermediates with each wood component. A modified multistage shrinking core model is employed to simulate biomass particle degradation. The reaction and kinetic regime of the hydrothermal liquefaction 2 (HTL) process are treated separately for each wood component. Although the lack of…
Heusler compounds as ternary intermetallic nanoparticles: Co2FeGa
2009
This work describes the preparation of ternary nanoparticles based on the Heusler compound Co2FeGa. Nanoparticles with sizes of about 20?nm were synthesized by reducing a methanol impregnated mixture of CoCl2 ? 6H2O, Fe(NO3)3 ? 9H2O and Ga(NO3)3 ? xH2O after loading on fumed silica. The dried samples were heated under pure H2 gas at 900??C. The obtained nanoparticles?embedded in silica?were investigated by means of x-ray diffraction (XRD), transmission electron microscopy, temperature dependent magnetometry and M??bauer spectroscopy. All methods clearly revealed the Heusler-type L21 structure of the nanoparticles. In particular, anomalous XRD data demonstrate the correct composition in addi…
Silica nanoparticle core structure examined by the E?Si? center 29Si strong hyperfine interaction
2015
Abstract β-Ray irradiation up to 1.2 GGy was employed to induce E′Si γ defects and to study the structure of silica nanoparticles with diameters from 7 up to 20 nm. Defect concentration and their 29 Si strong hyperfine doublet were investigated through electron paramagnetic resonance measurements. Our data indicate that stable defects are located in the nanoparticle core. Furthermore, the E′Si γ hyperfine interaction evidences that the core structure is denser than bulk silica and independent from the particle size. Finally, we put in evidence that the core structure is stable and unaffected by the irradiation in the investigated dose range maintaining the specific features of nanoparticles.
Nano-Jewels in Biology. Gold and Platinum on Diamond Nanoparticles as Antioxidant Systems Against Cellular Oxidative Stress
2010
Diamond nanoparticles (DNPs) obtained by explosive detonation have become commercially available. These commercial DNPs can be treated under Fenton conditions (FeSO(4) and H(2)O(2) at acidic pH) to obtain purer DNP samples with a small average particle size (4 nm) and a large population of surface OH groups (HO-DNPs). These Fenton-treated HO-DNPs have been used as a support of gold and platinum nanoparticles (≤2 nm average size). The resulting materials (Au/HO-DNP and Pt/HO-DNP) exhibit a high antioxidant activity against reactive oxygen species induced in a hepatoma cell line. In addition to presenting good biocompatibility, Au/HO- and Pt/HO-DNP exhibit about a two-fold higher antioxidant …
Synthesis, characterization and magnetism of monodispersed water soluble palladium nanoparticles
2008
Water soluble, monodispersed Pd nanoparticles with a narrow particle size distribution have been successfully synthesized by controlled reduction of [PdCl4]2−. The resulting aqueous colloids are stable over extended periods of time and can be prepared at high nanoparticle loading (20 g/L of Pd) with no agglomeration. The size of the nanoparticles can be reduced from the nanometer (ca. 3.5 nm) to the sub-nanometer size range (ca. 0.9 nm). Detailed magnetic characterization indicated that the larger, 3.5 nm nanoparticles show ferromagnetic properties at room temperature, while the sub-nanometric ones lose this magnetic behavior.