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1

Biological methods of ferric sulphate coagulant production with Thiobacillus ferrooxidans

100%
Wisniewski P., Nawrocki J., Grajek W.
Biotechnologia
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1995
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issue 3
140-151
EN
A packed-bed bioreactor with activated-carbon particles as a carrier matrix material inoculated with Thiobacillus ferroxidans was operated at a pH 1.30 to convert ferrous sulfate to ferric sulfate.The experimental variables were dillution rate, medium composition and Fe (I) ion concentration.The reactors were operated within a dillution rate range of 0.013 to 0.560/h and within a ferrous sulfate concentration range of 20 to 40 g/l.The aeration rate was 5-7 l/h.It was showed that replacement of the 9k medium with tap water had no negative effect on iron oxidation process.
2

RNA interference-based therapeutics in anticancer therapy

100%
Kaminska B., Kulesza D., Wisniewski P.
Biotechnologia
|
2010
|
issue 3
94-114
EN
RNA interference (RNAi) is a phenomenon of sequence-specific gene silencing and its discovery led to wide applications. Short interfering RNA (siRNA), which induces RNAi, has been experimentally introduced as a cancer therapy and is expected to be developed as a nucleic acid-based medicine. Potential success of siRNA cancer therapies depends on selection of appropriate gene targets and candidate targets include genes associated with cell proliferation, metastasis, angiogenesis, and drug resistance. In vivo systemic delivery of siRNA-based therapeutics to tumour tissues is challenging and the major limitations of siRNA therapeutic use are its degradation by serum nucleases, poor cellular uptake and rapid renal clearance following systemic administration. Several siRNA-based therapeutics are already in clinical trials. Further development of anti-cancer therapeutic siRNAs depends on development of nanocarriers, nuclease-resistant chemically modified siRNAs and variety of synthetic or natural lipids and polymers to systemically deliver siRNA. Here, we review potential approaches for delivery of RNAi based therapeutic in cancer therapy, results of current studies and clinical trials which demonstrate that the use of targeted siRNA offers promising strategies for cancer therapies.
3

Kinetics of biological iron oxidation in immobilized packed-bed reactors

100%
Nawrocki J., Wisniewski P., Grajek W., Astrib M.
Biotechnologia
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1995
|
issue 2
141-152
EN
A packed-bed bioreactors with activated carbon particles as a cerrier for iron-oxidizing bacteria was used for ferrous sulfate oxidation.The bioreactors were operated continuously for about 2 weeks.The experimental variables were: dillution rate, pH, medium composition and Fe(II) ions concentration.It was found that the efficiency of iron oxidation depended on the dilution rate and the medium pH.As dilution rate increased, the oxidation rate was decreased but at the same time reacto productivity was improved.The highest kinetic performance achieved in single stage fermentation related to the Fe(II) oxidation was over 90% when D was below 0.2/h.The pH optimum was 1.3. At higher pH values a ferric iron precipitation was accelerated.It was showed thet replacement of the 8K medium with tap water has not had a negative effect on iron oxidation process.
4
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Optimizing the Lightweight Ceramic Proppants Properties

100%
Wisniewski P., Szymanska J., Malek M., Mizera J.
Acta Physica Polonica A
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2016
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vol. 129
|
issue 4
501-503
EN
The paper presents results of sintering proppants parameters and its influence on light ceramic proppants obtained by the mechanical granulation method. The proppants were prepared basing on a ceramic composition consisting of three raw materials such as kaolin, clay and bauxite mixed with poly(vinyl alcohol) binder with a molecular weight 26000 g/mol and hydrolysis degree of 88%, added in amount of 5 wt% with respect to the powder. Sintering temperature range oscillated between 1200 and 1225°C, kiln rotations were 1-2 rpm. Sintered proppants were characterized in compliance with PN-EN ISO 13503-2 norm and bulk density, sphericity coefficient, turbidity, solubility in acids and scanning electron microscopy observations have been estimated. The results demonstrated that sintering temperature and kiln rotation have an essential effect of the proppants parameters.
5
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Investigation of the Basic Properties of Ceramic Proppants in Raw State Obtained by the Method of Mechanical Granulation

88%
Zarzycka D., Wisniewski P., Malek M., Szymanska J., Mizera J.
Acta Physica Polonica A
|
2016
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vol. 129
|
issue 4
552-555
EN
The investigation of fabricated ceramic materials, which can be used as proppants, is presented. Proppants are ceramic materials applied in hydraulic fracturing during extraction of shale gas. Solid slurry pumped with liquid into the deposit causes destruction of the rock structure. The role of proppants is to avoid closing of formed pores and as result enable gas migration from the deposit. Due to processing requirements and conditions in formations (high pressure and temperature), proppants should be characterized by proper physico-mechanical properties. The aim of this work was to elaborate the preparation method of ceramic materials, which can be used as proppants. In this paper results of properties studies of obtained proppants are presented. The influence of raw materials composition, especially the type of applied binder, was examined. Two types of green proppants obtained by the method of mechanical granulation without binder and with poly(vinyl alcohol) in amount of 5 wt% with respect to the powder were used. The properties: bulk density, roundness and sphericity coefficient, grain size and also structure and morphology of proppants was determined by the method of scanning electron microscopy with energy dispersive spectroscopy. The results indicate that composition of raw materials and type of binder have an important influence on the properties of obtained proppants in green state.
6
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Technological Properties of Ceramic Slurries Based on Silicon Carbide with Poly(vinyl alcohol) Addition for Shell Moluds Fabrication in Precision Casting Process

88%
Malek M., Wisniewski P., Szymanska J., Mizera J., Kurzydlowski K.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 4
528-530
EN
In this work technological properties of ceramic slurries based on silicon carbide powder with solid content 70 wt% were presented. These slurries were prepared for obtaining shell moulds in precision casting of Ni superalloys engine parts. The main binder was dispersion containing nanoalumina particles. Additionally poly(vinyl alcohol) with molecular weight 26000 g/mol as 5 wt% water solution was used as a rheological modifier. To characterize silicon carbide: scanning electron microscopy images, chemical composition, Zeta potential and grain size were studied. Technological properties of ceramic slurries i.e.: plate weight test, viscosity, dynamic viscosity, density and pH were investigated. Properties of silicon carbide based ceramic slurries are very promising and their shell moulds are very perspective for future application in aerospace industry.
7
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Relationship between Sample Morphology and Carrier Diffusion Length in GaN Thin Films

52%
Godlewski M., Goldys E., Phillips M., Böttcher T., Figge S., Hommel D., Czernecki R., Prystawko P., Leszczynski M., Perlin P., Wisniewski P., Suski T., Bockowski M., Grzegory I., Porowski S.
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|
issue 4-5
627-632
EN
Scanning and spot-mode cathodoluminescence investigations of homo- and hetero-epitaxial GaN films indicate a surprisingly small influence of their microstructure on overall intensity of a light emission. This we explain by a correlation between structural quality of these films and diffusion length of free carriers and excitons. Diffusion length increases with improving structural quality of the samples, which, in turn, enhances the rate of nonradiative recombination on structural defects, such as dislocations.
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