[Show abstract][Hide abstract] ABSTRACT: Nisoldipine is a dihydropyridine subclass calcium channel blocker with low oral bioavailability. Therefore, novel drug delivery systems able to enhance nisoldipine bioavailability are urgently needed. Here the nanoaerosol pulmonary administration of nisoldipine is investigated in experiments with WISTAR and ISIAH rats. The drug aerosol inhalation scheme includes an evaporation–condensation aerosol generator, inhalation chambers for rats, and aerosol spectrometer (to control aerosol concentration and size distribution). The particle mean diameter and number concentration are within the ranges 10–200 nm and 103–2×107 cm−3, respectively. The chemical composition of nanoaerosol particles was shown by means of liquid chromatography to be identical with the maternal drug. Using nose-only exposure chambers, the rat lung deposition efficiency was evaluated as a function of particle diameter. The dose-dependent effect from aerosolized nisoldipine was compared with that from the intravenous and oral drug delivery. In particular, it was found that nisoldipine aerosol administration is essentially more effective than traditional oral treatment, i.e. it gives the same blood pressure reduction as the oral treatment at the body deposited dose about 100 times less.
[Show abstract][Hide abstract] ABSTRACT: A procedure has been developed for determining the contact angle of a critical nucleus formed on seed particles during the heterogeneous nucleation of a vapor in a flow chamber. The procedure comprises the determination of the fraction of enlarged particles, as well as the selective separation of nanoparticles over sizes to locate the zone of intense nucleation. The concentration and size distribution of aerosol particles have been measured with a diffusion spectrometer of aerosols. Vapor concentration distributions and supersaturation fields have been determined by solving the mass-transfer problem. The calculated supersaturation fields are in good agreement with the location of the intense nucleation zone experimentally found with the help of selective separation. The fractions of enlarged particles have been determined as functions of supersaturation in the chamber. A formula has been derived for calculating the fraction and size distribution function of enlarged particles at known supersaturation and temperature fields and a preset contact angle. The contact angles are selected in a manner such that the calculated fraction of enlarged particles coincides with that measured experimentally. It has been revealed that the contact angle of critical sulfur nuclei formed on tungsten oxide seed particles with average radii aOE (c) R (p)> a parts per thousand 5.8-4.4 nm is in a range of 21.2-20.5A degrees, while, in the case of sodium chloride seed particles with aOE (c) R (p)> a parts per thousand 6.0-4.4 nm, the contact angle is 20.4-17.4A degrees. The size of a critical nucleus has been found to be proportional to calculated average radius of a seed particle aOE (c) R (p)> in both cases.
[Show abstract][Hide abstract] ABSTRACT: Isothermal nucleation of supersaturated ibuprofen racemate vapor has been experimentally studied in a flow diffusion chamber at 293.3 and 301.2 K. Nucleation rates have been measured in the range of 104−104 cm−3 s−1 as functions of supersaturation. According to the first nucleation theorem, the numbers of molecules in critical nuclei have been found and used to determine the nucleation rate and supersaturation values as depending on the sizes of critical nuclei. The comparison of the experimental data with theoretical predictions has shown that the nucleation rates measured as functions of the numbers of molecules in critical nuclei are higher than the rates predicted by the classical theory by six to seven decimal orders of magnitude but, within one order of magnitude, coincide with the rates predicted by a theory previously proposed in a work by one of the authors, in which nucleation clusters were considered to be microscopic objects.
[Show abstract][Hide abstract] ABSTRACT: Homogeneous nucleation of ibuprofen vapor is studied in a nucleation flow chamber, a horizontal quartz tube equipped with an external heater. The area of the chamber where the nucleation proceeds most efficiently is determined, and the volume of this area is estimated. The temperature and supersaturation are determined and the homogeneous nucleation rate is calculated for this area. Saturation vapor pressure over liquid ibuprofen is measured in a temperature range of 353–383 K. Using an exact formula that has recently been derived for the nucleation rate based on the works by Kusaka, Reiss, as well as the Frenkel liquid-kinetics theory, surface tension and the radius of surface of tension of a critical nucleus σ= 25.9 mN/m and R
s = 1.6 nm, respectively, are calculated at 318 K. The measurement of the surface tension of an ibuprofen planar surface shows that, at 318 K, σ∞ = 24.38 mN/m; i.e., σ is higher than σ∞ by 6%. A critical nucleus is established as containing nearly 36 ibuprofen molecules.
[Show abstract][Hide abstract] ABSTRACT: We developed a method for studying heterogeneous nucleation in a laminar flow chamber, which allows one to determine the relationship between the main parameters of the process, i.e., the critical size of a seed particle, supersaturation, and the temperature. The workability of this method is demonstrated for the heterogeneous nucleation of sulfur vapor on nanoparticles of tungsten oxide.
Atmospheric and Oceanic Optics 11/2012; 25(6). DOI:10.1134/S1024856012060115
[Show abstract][Hide abstract] ABSTRACT: The homogeneous nucleation of bismuth supersaturated vapor is studied in a laminar flow quartz tube nucleation chamber. The concentration, size, and morphology of outcoming aerosol particles are analyzed by a transmission electron microscope (TEM) and an automatic diffusion battery (ADB). The wall deposit morphology is studied by scanning electron microscopy. The rate of wall deposition is measured by the light absorption technique and direct weighting of the wall deposits. The confines of the nucleation region are determined in the "supersaturation cut-off" measurements inserting a metal grid into the nucleation zone and monitoring the outlet aerosol concentration response. Using the above experimental techniques, the nucleation rate, supersaturation, and nucleation temperature are measured. The surface tension of the critical nucleus and the radius of the surface of tension are determined from the measured nucleation parameters. To this aim an analytical formula for the nucleation rate is used, derived from author's previous papers based on the Gibbs formula for the work of formation of critical nucleus and the translation-rotation correction. A more accurate approach is also applied to determine the surface tension of critical drop from the experimentally measured bismuth mass flow, temperature profiles, ADB, and TEM data solving an inverse problem by numerical simulation. The simulation of the vapor to particles conversion is carried out in the framework of the explicit finite difference scheme accounting the nucleation, vapor to particles and vapor to wall deposition, and particle to wall deposition, coagulation. The nucleation rate is determined from simulations to be in the range of 10(9)-10(11) cm(-3) s(-1) for the supersaturation of Bi(2) dimers being 10(17)-10(7) and the nucleation temperature 330-570 K, respectively. The surface tension σ(S) of the bismuth critical nucleus is found to be in the range of 455-487 mN/m for the radius of the surface of tension from 0.36 to 0.48 nm. The function σ(S) changes weakly with the radius of critical nucleus. The value of σ(S) is from 14% to 24% higher than the surface tension of a flat surface.
The Journal of Chemical Physics 06/2012; 136(22):224506. DOI:10.1063/1.4725535 · 2.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The evaluation and prediction of air quality in settlements requires our awareness of the main pollutant sources and their power changing with time (anthropogenic sources) or under the influence of environmental conditions (natural sources). In seaside cities, aerosol of sea origin is one of significant sources of air pollutants. Complex estimation of different atmospheric boundary layer pollutants in Gelendzhik was carried out in the first decade of July 2009. The conducted investigations showed that in the period of observations the portion of sea aerosol made up from 4 to 25% of the total aerosol. These data correlated well with similar data for the Mediterranean. It was found that pollutant concentrations in aerosol were considerably lower than the corresponding average daily maximum permissible concentrations values.
3rd Biannual International Conference on Advanced Atmospheric Aerosol; 01/2010
[Show abstract][Hide abstract] ABSTRACT: The diffusion coefficient of WOx, Pt and NaCl particles in the diameter range of 3 to 84 nm was determined from the penetration of a set of wire screens in the temperature range of 295 to 600 K. The temperature dependence could be approximated well by a power law D ~ T α , where α decreases from 1.7 to 1.55 with increasing particle diameter. This dependence differs significantly from the predictions of various correlations, and in par-ticular the Cunningham-Millikan-Davies (CMD) correlation. A modification to the CMD correlation is suggested which includes temperature dependent empirical coefficients.
[Show abstract][Hide abstract] ABSTRACT: The diffusion coefficient of WOx, Pt, and NaCl particles in the diameter range from 3 to 84 nm, determined from the penetration through a set of wire screens in the temperature range 295–600 K were recalculated with account for polydispersity of the used particles. Neglecting of polydispersity in Rudyak, Dubtsov, and Baklanov (2009) resulted in overestimation in the reported diffusion coefficient values by 10–15%. This difference, however, does not depend on the temperature in the range 300–600 K. However this decrease does not exceed the experimental error and, most importantly, the exponent of the T dependence remains almost unchanged.
[Show abstract][Hide abstract] ABSTRACT: We present comprehensive experimental and theoretical studies of poly(methyl methacrylate) (PMMA) ablation by single pulses of 9.17 µm laser radiation in a wide range of fluences. Ablation was carried out in a quartz cell through which nitrogen under atmospheric pressure was pumped. The composition of the ablation products was analysed with the use of an automatic diffusion battery. Both the irradiated surface and the substrate with the deposited ablation products were examined by transmission electron microscopy. Different aspects and stages of ablation have been investigated: laser heating and vaporization of the PMMA surface, mechanisms of ablation, dynamics of the laser-induced plume, nanoparticle formation in the plume and/or ejection from the irradiated surface. It has been found that the size distribution of nanoparticles formed during ablation changes its form from a single peak to a bimodal shape with increasing laser fluence. The transformation of the size distribution is analysed with the help of thermal and gasdynamic modelling which gives a basis for insight into the mechanisms and dynamics of ablation.
Journal of Physics D Applied Physics 03/2009; 42(6-6):65504-16. DOI:10.1088/0022-3727/42/6/065504 · 2.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Aerosol lung administration is a convenient way to deliver water-insoluble or poorly soluble drugs, provided that small-sized particles are generated. Here, for the outbred male mice, we show that the pulmonary administration of ibuprofen nanoparticles requires a dose that is three to five orders of magnitude less than that for the orally delivered particles at the same analgesic effect.
The aerosol evaporation-condensation generator consisted of a horizontal cylindrical quartz tube with an outer heater. Argon flow was supplied to the inlet and aerosol was formed at the outlet. The particle mean diameter and number concentration varied from 10 to 100 nm and 10(3)-10(7) cm(-)3, respectively. The analgesic action and side pulmonary effects caused by the inhalation of ibuprofen nanoparticles were investigated.
The chemical composition of aerosol particles was shown to be identical with the maternal drug. Using the nose-only exposure chambers, the mice lung deposition efficiency was evaluated as a function of the particle diameter.
The dose-dependent analgesic effect of aerosolized ibuprofen was studied in comparison with the oral treatment. It was found that the dose for aerosol treatment is three to five orders of magnitude less than that required for oral treatment at the same analgesic effect. Accompanying effects were moderate venous hyperemia and some emphysematous signs.
Journal of Aerosol Medicine and Pulmonary Drug Delivery 03/2009; 22(3):245-53. DOI:10.1089/jamp.2008.0721 · 2.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The respiratory system provides entry for drug nanoparticles to cure systemic diseases. The modern devices that are available on the market of therapeutic aerosol delivery systems have a number of disadvantages. There remains a need for an alternative means that is low cost, convenient, and capable of producing small-sized particles. On the other hand, one-third of the modern drugs are poorly water soluble. Many currently available injectable formulations of such drugs can cause side effects that originate from detergents and other agents used for their solubilization. The aerosol lung administration may by a good way for delivery of the water-insoluble drugs. We present here a new way for the generation of drug nanoparticles suitable for many water insoluble substances based on the evaporation-condensation route. In this paper the indomethacin nanoaerosol formation was studied and its anti-inflammatory effect to the outbred male mice was examined. The evaporation-condensation aerosol generator consisted of a horizontal cylindrical quartz tube with an outer heater. Argon flow was supplied to the inlet and the aerosol was formed at the outlet. The particle mean diameter and number concentration were varied in the ranges 3 to 200 nm and 10(3) to 10(7) cm(-3), respectively. The liquid chromatography and X-ray diffraction methods have shown the nanoparticles consist of the amorphous phase indomethacin. The aerosol lung administration experiments were carried out in the whole-body exposure chamber. Both the lung deposited dose and the particle deposition efficiency were determined as a function of the mean particle diameter for mice being housed into the nose-only exposure chambers. The anti-inflammatory action and side pulmonary effects caused by the inhalation of indomethacin nanoparticles were investigated. It was found that the aerosol administration was much more effective than the peroral treatment. The aerosol route required a therapeutic dose six orders of magnitude less than that for peroral administration.
Journal of Aerosol Medicine and Pulmonary Drug Delivery 09/2008; 21(3):231-43. DOI:10.1089/jamp.2007.0672 · 2.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The temperature dependence of the diffusion coefficient of nanoparticles in gases has been experimentally studied. It is established
that this dependence significantly differs from that predicted by various correlations, in particular, by the Cunningham-Millikan-Davies
correlation that is used as an instrumental basis for virtually all methods of measurement of the diffusion coefficient in
[Show abstract][Hide abstract] ABSTRACT: Formation of aerosol nanoparticles as well as carbon nanotubes and nanofilaments is studied during co-pyrolysis of iron pentacarbonyl and propane with argon as a carrier gas in a flow reactor. Gaseous intermediates from propane thermal decomposition (CH 4 , C 2 H 6 and C 3 H 4) and Fe(CO) 5 conversion are monitored by gas chromatography and IR-spectroscopy, respectively. The aerosol morphology is studied by transmission electron microscopy (TEM) and high resolution TEM. The aerosol particle concentration and size distribution are measured by an automated diffusion battery. The crystal phase composition of particles is studied by x-ray diffractometry. The decomposition of the Fe(CO) 5 + Ar mixture resulted in an iron aggregate formation composed of fine primary particles. In the case of lower pyrolysis temperatures, about 450 K, the primary particle mean diameter is about 10 nm, and consequently, the majority of the primary particles are superparamagnetic, thus forming compact aggregates. At intermediate pyrolysis temperatures in the range 800–1040 K the primary particle diameter is about 20–30 nm, and most of the particles are ferromagnetic in nature. The coagulation of these particles results in a chain-like aggregate formation. Finally, at temperatures higher than the Curie point (1043 K) the ferromagnetic properties vanish and the formation of compact aggregates is observed again. The co-pyrolysis of Fe(CO) 5 and C 3 H 8 mixed with Ar carrier gas resulted in aerosol aggregate structures dramatically different from those formed by iron pentacarbonyl pyrolysis. In particular, in the temperature range 1070–1280 K, we observed Fe 3 C particles connected by long carbon nanotubes (CNTs). The aggregate morphology is described in terms of a fractal-like dimension D f , which is determined from TEM images on the basis of a scaling power law linking the aggregate mass (M) and radius (R), M∼R D f . The Fe 3 C–CNT aggregate morphology is a function of the inlet ratio between propane and iron pentacarbonyl concentrations [C 3 H 8 ] 0 /[Fe(CO) 5 ] 0 . At the low ratio of [C 3 H 8 ] 0 /[Fe(CO) 5 ] 0 < 80 the fractal dimension of aggregates decreases (from 1.7 down to about 1) with the increasing ratio of inlet concentrations. This effect, as observed by TEM, is due to the increase in the mean nanotube length. Vice versa, in the range C 3 H 8 ] 0 /[Fe(CO) 5 ] 0 > 80 the fractal aggregate dimension is higher for a larger ratio of [C 3 H 8 ] 0 /[Fe(CO) 5 ] 0 , which is explained by the larger thickness of growing nanotubes obtained for a relatively large propane concentration. The aggregate formation mechanism includes consecutive stages of iron aggregate formation due to Fe(CO) 5 decomposition, carbon deposition on iron particles from C 3 H 8 pyrolysis intermediates, carbon dissolution in iron particles, nanotube nucleation at the carbon concentration of about 60 at.% in Fe–C solution and disruption of the Fe–C aggregates into small pieces by the growing nanotubes.
Journal of Physics D Applied Physics 04/2007; 40(7):2071-2082. DOI:10.1088/0022-3727/40/7/032 · 2.72 Impact Factor