Regina Lech-Przywara

Mrs. Regina Lech-Przywara

orcid

Research Focus & Metrics

Academic Career Length

4Years (2023-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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3 July 2023 in Agriengineering
Verified
Journal Article
Open access
PDF file
MPMateusz Przywara
Mateusz Przywara
RLRegina Lech-Przywara
Regina Lech-Przywara
WZWojciech Zapała
Wojciech Zapała
IOIreneusz Opaliński
Ireneusz Opaliński
The objective of the study was to examine the influence of moisture content on the mechanical properties of solid biomass, which is important for storage and handling. Mechanical properties involving powder flowability were determined with a Jenike shear tester. The materials tested were powdered biomass: sunflower husks, apple pomace, dried distillers grains with solubles (DDGS), and meat and bone meal. In static operations in which powdered biomass is generally under a significant load, such as in silos, moisture deteriorates the mechanical properties of biomass and increases its cohesion. In the case of DDGS, an additional slight decrease in stress was observed for samples with the highest moisture content, which was above 20%. For meat and bone meal and sunflower husks, a lubrication phenomenon was clearly observed, in which biomass samples with increased moisture content manifested better flowability, requiring lower boundary shear stresses than less moist samples. For apple pomace samples, with normal stresses above 50 kPa, the addition of moisture above 10% did not change the values of the observed shear stresses, indicating the stability of their properties. The use of powdered biomass with higher moisture contents, at above 10%, should be avoided, as such material can lead to overhangs in tanks and silos.

25 July 2025 in Molecules
Verified
Journal Article
Open access
PDF file
MPMateusz Przywara
Mateusz Przywara
RLRegina Lech-Przywara
Regina Lech-Przywara
PRPatrycja Rupar
Patrycja Rupar
WZWojciech Zapała
Wojciech Zapała
The uniform distribution of APIs is essential in tablet formulations, particularly in direct compression, where powder blending is the only means of ensuring dose homogeneity. This study evaluated the influence of three mixing techniques—V-type mixer, planetary ball mill, and vibratory ball mill—on the physical properties and content uniformity of naproxen sodium tablets. Blends consisting of naproxen sodium, cellulose, PVP, calcium carbonate, and magnesium stearate were prepared under varied mixing intensities and characterized in terms of flowability, compressibility, and particle size distribution. The resulting tablets were analyzed for weight, thickness, hardness, friability, and API content using a simplified bypass HPLC method. The V-type mixer yielded tablets with the most consistent weight and thickness, despite the poorest blend flow properties. Vibratory milling produced the hardest tablets and best API content uniformity, although high-energy processing introduced variability at longer mixing times. The analytical method proved fast and robust, allowing for reliable API quantification without full chromatographic separation. These findings underscore the need to balance mechanical blending energy with formulation properties and support the use of streamlined analytical strategies in pharmaceutical development.

21 February 2023 in Agriengineering
Verified
Journal Article
Open access
PDF file
MPMateusz Przywara
Mateusz Przywara
RLRegina Lech-Przywara
Regina Lech-Przywara
Marcin ChutkowskiMarcin Chutkowski
Marcin Chutkowski
WZWojciech Zapała
Wojciech Zapała
IOIreneusz Opaliński
Ireneusz Opaliński
Utilization of agricultural waste can be done by converting it with conventional fuels to energy. For this purpose, it is necessary to understand the properties of waste and its mixture with the fossil fuels important for its storage and conversion. The objective of the work was to examine the influence of moisture content and the composition of agricultural waste with hard coal mixtures on the mechanical and rheological properties of the waste. The materials tested were powdered biomass: dried distillers grains with solubles (DDGS), meat and bone meal (MBM), and hard coal (HC). Mechanical properties were measured to investigate flowability with the Jenike shear tester. A technique with an annular powder rheometer was applied for rheological measurements. It was shown that an increased moisture content worsened the flowability of the mixtures, while an increased biomass content reduced the influence of moisture and stabilized the mechanical properties of the mixtures in quasi-static conditions. In dynamic conditions, moisture decreased the mechanical strength of the mixtures and increased their flowability.

2 July 2025 in Preprints.org
Verified
Preprint
Open access
PDF file
MPMateusz Przywara
Mateusz Przywara
RLRegina Lech-Przywara
Regina Lech-Przywara
PRPatrycja Rupar
Patrycja Rupar
WZWojciech Zapała
Wojciech Zapała
The uniform distribution of active pharmaceutical ingredients (APIs) is essential in tablet formulations, particularly in direct compression, where powder blending is the only means of ensuring dose homogeneity. This study evaluated the influence of three mixing techniques—V-type mixer, planetary ball mill, and vibratory ball mill—on the physical properties and content uniformity of naproxen sodium tablets. Blends consisting of naproxen sodium, cellulose, PVP, calcium carbonate, and magnesium stearate were pre-pared under varied mixing intensities, and characterized in terms of flowability, com-pressibility, and particle size distribution. Resulting tablets were analyzed for weight, thickness, hardness, friability, and API content using a simplified bypass HPLC method. The V-type mixer yielded tablets with the most consistent weight and thickness, despite the poorest blend flow properties. Vibratory milling produced the hardest tablets and best API content uniformity, although high-energy processing introduced variability at longer mixing times. The analytical method proved fast and robust, allowing for reliable API quantification without full chromatographic separation. These findings underscore the need to balance mechanical blending energy with formulation properties, and support the use of streamlined analytical strategies in pharmaceutical development.

1 June 2025 in Advances in Science and Technology Research Journal
Verified
Journal Article
Open access
RLRegina Lech-Przywara
Regina Lech-Przywara
WZWojciech Zapała
Wojciech Zapała
This study examines the influence of temperature, eluent modifier type and concentration, and mobile phase flow velocity on the separation efficiency of caffeine (CAF) and phenol (PH) in Hypersil GOLD HILIC and Shodex SILICA 5NH 4D chromatographic columns. A thermodynamic analysis demonstrated...

15 May 2024 in Agriengineering
Verified
Journal Article
Open access
PDF file
MPMateusz Przywara
Mateusz Przywara
RLRegina Lech-Przywara
Regina Lech-Przywara
WZWojciech Zapała
Wojciech Zapała
Numerical investigations on the flowability of pulverized biomass are crucial for agriculture, aiding in optimizing biomass use, crop residue management, soil health improvement, and environmental impact mitigation. Rising interest in biomass and conversion processes necessitates deeper property understanding and technological process optimization. Moisture content is a key parameter influencing biomass quality. In this paper, computer simulations of shear tests depending on the moisture content using the discrete element method were carried out and compared with experimental results. An experimental study and modeling for Jenike’s direct shearing apparatus was carried out. A swelling bed model was proposed to account for the effect of moisture. The swelling bed model assumed an increase in biomass grain vorticity proportional to the moisture content. The model was solved using the discrete element method (DEM). The model considers the effect of moisture on the values of Young’s and Kirchoff’s moduli for biomass grains. The model assumed that moisture is not present in surface form, the total amount of moisture is absorbed into the interior of the material grains, and the volume of a single grain increases linearly with an increase in the volume of the absorbed moisture. The tested materials were pulverized sunflower husks, apple pomace, distiller’s dried grains with solubles (DDGS), meat and bone meal (MBM), and sawdust. Samples with moisture contents of 0%, 10%, 20%, and 30% were tested. The best agreement of the model with the experimental data was observed for the most absorbent materials in which moisture was not present in surface form, such as apple pomace, DDGS, and sawdust. Research data are important for the proper design of biomass storage, transportation equipment, and utilization as feedstock for bioenergy production or soil enrichment.