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Rifamycin antibiotics—new compounds and synthetic methods. Part 3: Study of the reaction of 3-formylrifamycin SV with primary amines and ketones
No full textabstractEN: In the third stage of our study concerning the search for new antibacterial rifamycin antibiotics, the reactions of 3-formylrifamycin SV (1) with a range of primary alkylamines and ketones of general structure R1–CH2–CO–R2 (R1H or alkyl and R2alkyl or aryl) has been investigated. A new synthetic method for the preparation of a new group of rifamycin derivatives with an α,β-unsaturated imine substituent at C-3 has been developed. These compounds showed a tendency to reversibly isomerise in organic solvents and, in the presence of water, to rapidly hydrolyse. The structures of four isolated microcrystalline compounds 2, 3, 4, 5 and a reaction's mechanism have been proposed on the basis of mass spectrometry results as well as (1D) and (2D) 1H and 13C NMR analysis. The new synthetic route reported herein is a promising pathway to new reactive rifamycins displaying broader capabilities than the plain 3-formylrifamycin SV.score: 30collation: 5925-593
Broad-Band Dielectric Probe with a Coaxial Line - Circular Waveguide Junction
No full textabstractEN: A model of a broad-band dielectric probe for permittivity measurements of liquids and powdered materials at microwave frequencies is presented in the paper. The coaxial line - circular waveguide junction, built in the probe, is studied using full-wave analysis. A layer of material under test is placed in the circular waveguide of arbitrary radius The probe has been modeled in order to predict the relationship between reflection coefficient at the input and the complex permittivity of any dielectric sample. The developed model was verified with measurements on air, methanol and distilled water.score: 3collation: 1-
Piezoelectric control of composite plate vibration: Effect of electric potential distribution
No full textabstractEN: The paper deals with the vibration analysis of active rectangular plates. The plates considered are composites containing piezoelectric sensor/actuator layers, which operate in a velocity feedback control to achieve transverse vibration suppression. The piezoelectric layers are poled through the thickness and equipped with traditional surface electrodes. In order to satisfy the Maxwell electrostatics equation the widely used simplification of the electric potential distribution in the actuator layer (linear across the thickness) is replaced by a combination of a half-cosine and linear distribution in the transverse direction. The in-plane spatial variation of the potential instead of applying uniform distribution is determined by the solution of the coupled electromechanical governing equations with the natural boundary conditions corresponding to both the flexural and electric potential fields. The analysis is performed for simply supported plates. Two models of the plate are considered. In the first case the displacement field is based on the Kirchhoff hypothesis. For the second the Mindlin plate model is applied. The governing coupled equations describing the active plate behaviour are derived. The influence of the electric potential distribution and also the thickness of piezoelectric layers on the plate dynamics including the natural frequencies modification is numerically investigated and discussed.score: 35collation: 948-95
Simulation of vehicle: Track interaction in the medium frequency range with application to analysis of mechanical and thermal loading in contact
No full textscore: 3collation: 641-65
Hydrodynamical model of pulmonary clearance
No full textabstractEN: The theoretical description of the behaviour of a thin liquid film covered with a monomolecular surfactant layer is presented. This film is subjected to oscillatory compressions and tensions. It follows from the solution of this model that a net outflow of liquid from the film takes place. The size of this outflow has been estimated for variable parameters of the model. The optimum value of the displacement as a function of the Ma/Re Sc factor has been found. The model was adapted to the phenomenon of alveoli clearance.score: 35collation: 741-74
The activation of CH bonds in internal alkenes and dienes by \NiCp\ species formed in the reaction of nickelocene with alkali metals
No full textabstractEN: Reactions of nickelocene with metallic sodium in the presence of internal alkenes: trans-3-hexene, cis-2-heptene and 2,3-dimethyl-2-butene have been studied. It was found that \NiCp\ species generated in the reaction of nickelocene with sodium dehydrogenate internal alkenes to alkynes. The latter form then complexes with tri(cyclopentadienylnickel) (NiCp)3RCCR and with di(cyclopentadienylnickel) (NiCp)2RCCR. If the methyl group is adjacent to the alkene double bond, the activation of the CH bonds of this group leads to the formation of alkylidyne tri(cyclopentadienylnickel) clusters. In the reaction of nickelocene with lithium in the presence of 1,5-hexadiene, alkylidyne tri(cyclopentadienylnickel) cluster (NiCp)3CCH2CH2CH2CHCH2 and intramolecularly stabilised complex CpNiCH(CH3)CH2CH2CHCH2 were formed. In all the reactions studied di-, (NiCp)2CpH, and tetra(cyclopentadienylnickel), (NiCp)4Hx, compounds were formed besides the other products.score: 30collation: 249-25
Dynamics of oropharyngeal aerosol transport and deposition with the realistic flow pattern
No full textabstractEN: Aerosol flow and deposition in the model of human oropharynx was studied theoretically and experimentally for two realistic inspiratory patterns. The three-dimensional (3D) airflow structure in the sample geometry was solved with the computational fluid dynamics (CFD) code (Fluent), used to calculate dynamic distribution of particle deposition (0.3–10 μm). Experiments were done for the same flow conditions using the silicone-rubber cast with the matching geometry. Nonsteady breathing flows were reproduced with the computer-controlled artificial lung apparatus. Results of computations show that particles smaller than 3 μm easily pass the oropharynx during inspiration, while particles with a size close to 10 μm are substantially deposited, preferentially in the region of the naso-pharyngeal bend. For particles in the submicrometer size range, the spatial and temporal deposition pattern is more complicated, and strongly depends on breathing dynamics. The experiments confirmed that the mass median diameter (M...score: 25collation: 773-78
Mechanims of aerosol particle deposition in the oro-pharynx under non-steady airflow
No full textabstractEN: Comparison of experimental and computational results of aerosol deposition in the oro-pharyngeal cast of human published recently (Sosnowski TR, Moskal A, Gradoń L. (2006) Inhal Toxicol; 18: 773–780) demonstrated the applicability and relevance of considering realistic breathing patterns in analysis of aerosol flow and deposition within the human head airways. This issue is extended in the current paper, focused on a detailed analysis of spatial and temporal distribution of particle deposition in the oro-pharynx during inspiration. CFD modeling was used to determine both the 3D airflow structure and the local particle deposition fluxes at two different inspiratory patterns. Behavior of aerosol (particle size: 0.3–10 μm, material density: 2200 kg m−3) was analyzed applying Lagrangian approach and considering Brownian effects for submicron particles. Results indicate that particles of different sizes are deposited in different parts of the oro-pharynx, depending on the point in the inspiration cycle. Larger particles (3–10 μm) are separated efficiently in the naso-pharyngeal bend due to inertia, which predominate in the middle phase of inspiration. Submicron particles are deposited more uniformly in the oro-pharyngeal space, and their separation from the air is enhanced in a short transition period between inspiration and expiration. It suggests the importance of mixing of inspired and expired air streams for particle deposition pattern. Comparison of our computational results of deposition to the approximation derived from the in vivo data (Stahlhofen W, Rudolf G, James AC. (1989) J Aerosol Med; 2: 285–308) shows a good agreement for particles, for which the inertia is a predominant mechanism of deposition. The results of this work lead to a more detailed description of the dynamics of oro-pharyngeal aerosol deposition during inspiratory part of the breathing cycle. The recognition of that problem is essential for prediction of toxic or pharmacological local effects of inhaled aerosols.score: 25collation: 19-2
Long-term three-dimensional cell culture and anticancer drug activity evaluation in a microfluidic chip
No full textabstractEN: In this work, we present a microfluidic array of microwells for long-term tumor spheroid cultivation and anticancer drug activity evaluation. The three-dimensional microfluidic system was obtained by double casting of poly(dimethylsiloxane). Spheroids of HT-29 human carcinoma cells were cultured in the microsystem for four weeks. After two weeks of the culture growth slowdown and stop were observed and high cell viability was determined within next two weeks. The characteristics of a homeostasis-like state were achieved. A cytostatic drug (5-fluorouracil) was introduced into the microsystem with different frequency (every day or every second day) and different concentrations. The geometry and construction of the microsystem enables flushing away of unaggregated (including dead) cells while viable spheroids remain inside microwells and decreasing spheroid diameter can be observed and measured as an indicator of decreasing cell viability. The results have shown differences in response of spheroids to different concentrations of 5-fluorouracil. It was also observed, that higher frequency of drug dosing resulted in more rapid spheroid diameter decrease. The presented microfluidic system is a solution for cell-based studies in an in vivo-like microfluidic environment. Moreover, observation of decreasing spheroid dimensions is a low-cost, label-free and easy-to-conduct mean of a quantitative determination of a 3D cellular model response to a applied drug. It is suitable for long-term observation of spheroid response, in a contrary to other viability assays requiring termination of a culture.score: 40collation: 68-7
Bonding-less (B-less) fabrication of polymeric microsystems
No full textabstractEN: A new technology of the microsystems fabrication was developed. The process is based on a so-called capillary film, which is a commercially available material. A matrix, master pattern corresponding to the microchannels structure, made of the capillary film emulsion is embedded inside a block of polydimethylsiloxane (PDMS). After polymer cross-linking, the matrix is dissolved and removed as a solution from the PDMS structure leaving network of empty spaces that can act as microchannels. In the paper, the fabrication methods of the microsystems with 2D or sandwich-like microchannels architecture were described.score: 0collation: 733--73