Lukasiewicz Research Network – PORT Polish Center for Technology Development
Recent publications
Staphylococcal biofilms are major causative factors of non-healing wound infections. Their treatment algorithms recommend the use of locally applied antiseptic agents to counteract the spread of infection. The efficacy of antiseptics against biofilm is assessed in vitro by a set of standard quantitative and semi-quantitative methods. The development of software for image processing additionally allowed for the obtainment of quantitative data from microscopic images of biofilm dyed with propidium iodine and SYTO-9 reagents, differentiating dead cells from live ones. In this work, the method of assessment of the impact of antiseptic agents on staphylococcal biofilm in vitro, based on biofilms’ processed images, was proposed and scrutinized with regard to clinically relevant antiseptics, polyhexanide, povidone–iodine and hypochlorite. The standard quantitative culturing method was applied to validate the obtained data from processed images. The results indicated significantly higher activity of polyhexanide and povidone–iodine than hypochlorite against staphylococcal biofilm. Taking into account the fact that in vitro results of the efficacy of antiseptic agents against staphylococcal biofilm are frequently applied to back up their use in hospitals and ambulatory units, our work should be considered an important tool; providing reliable, quantitative data in this regard.
Composite silica-titania waveguide films of refractive index ca. 1.8 are fabricated on glass substrates using a sol-gel method and dip-coating technique. Tetraethyl orthosilicate and tetraethyl orthotitanate with molar ratio 1:1 are precursors. Fabricated waveguides are annealed at 500 °C for 60 min. Their optical properties are studied using ellipsometry and UV-Vis spectrophotometry. Optical losses are determined using the streak method. The material structure and chemical composition, of the silica-titania films are analyzed using transmission electron microscopy (TEM) and electron dispersive spectroscopy (EDS), respectively. The surface morphology was investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM) methods. The results presented in this work show that the waveguide films are amorphous, and their parameters are stable for over a 13 years. The optical losses depend on their thickness and light polarization. Their lowest values are less than 0.06 dB cm−1. The paper presents the results of theoretical analysis of scattering losses on nanocrystals and pores in the bulk and interfaces of the waveguide film. These results combined with experimental data clearly indicate that light scattering at the interface to a glass substrate is the main source of optical losses. Presented waveguide films are suitable for application in evanescent wave sensors.
High-yielding and scalable methods for iterative synthesis of sequence-defined macromolecules is a great challenge in modern polymer chemistry. Sequence-defined macromolecules are fabricated by multi-step iterative processes that involve high reagents and solvents consumption. Moreover, every step causes yield losses that result in low overall yield. Despite the envisioned valuable functions and applications of sequence-defined polymers, the synthetic limitations constitute a barrier for the exploitation of their practical potential. Here, we investigated the one-pot synthesis of oligocarbamates without the purification of intermediates. To control monomer sequence without isolation, we introduced a monitoring feedback loop to fuel the exact amount of reagents to the reaction mixture, assuring full conversion of each reaction. Based on a one-pot strategy, we have developed a facile approach for the preparation of uniform, oligocarbamates with full control of monomer order and defined stereochemistry. The great advantage of the presented methodology is the scalability of the process (demonstrated for synthesis of 50 g) and high yield (up to 90%). Oligomers obtained on a large scale can be further used as precursors for the synthesis of polymers with high molar mass. One-pot methods combined with chemoselective reactions bear the potential to overcome existing synthesis limitations and unlock the practical use of sequence-defined macromolecules. The presented concept might be further extended to different multi-step processes.
High-yielding and scalable methods for iterative synthesis of sequence-defined macromolecules is a great challenge in modern polymer chemistry. Sequence-defined macromolecules are fabricated by multi-step iterative processes that involve high reagents and solvents consumption. Moreover, every step causes yield losses that result in low overall yield. Despite the envisioned valuable functions and applications of sequence-defined polymers, the synthetic limitations constitute a barrier for the exploitation of their practical potential. Here, we investigated the one-pot synthesis of oligocarbamates without the purification of intermediates. To control monomer sequence without isolation, we introduced a monitoring feedback loop to fuel the exact amount of reagents to the reaction mixture, assuring full conversion of each reaction. Based on a one-pot strategy, we have developed a facile approach for the preparation of uniform, oligocarbamates with full control of monomer order and defined stereochemistry. The great advantage of the presented methodology is the scalability of the process (demonstrated for synthesis of 50 g) and high yield (up to 90%). Oligomers obtained on a large scale can be further used as precursors for the synthesis of polymers with high molar mass. One-pot methods combined with chemoselective reactions bear the potential to overcome existing synthesis limitations and unlock the practical use of sequence-defined macromolecules. The presented concept might be further extended to different multi-step processes.
Here we present new findings of a comprehensive study of the fundamental physicochemical properties for GeS and GeSe in bulk form. UV and X-ray photoelectron spectroscopies (UPS/XPS) were employed for the experiments, which were carried out on in situ cleaned (100) surfaces free from contamination. This allowed to obtain reliable results, also unchanged by effects related to charging of the samples. The work functions, electron affinities and ionization energies as well as core level lines were found. The band gaps of the investigated materials were determined by photoreflectance and optical absorption methods. As a result, band energy diagrams relative to the vacuum level for GeS and GeSe were constructed. The diagrams provide information about the valence and conduction band offsets, crucial for the design of various electronic devices and semiconducting heterostructures.
Current study aimed to evaluate the utilization of protein from brewers' spent grain (BSGP) on microstructural formation as well as rheological behavior, acidity and lactic acid bacteria (LAB) profile during the refrigerated storage. Three different BSGPs were provided including BSGP-C (extracted without enzymatic hydrolysis), BSGP-P (with protease), and BSGP-PF (with protease co-incubated with flavourzyme). The results demonstrated that BSGPs improved lactic acid forming capability in yogurt production to a higher level than milk-protein based enrichment. BSGPs improved the growth and survival of lactic acid bacteria (LAB), particularly BSGP-P in improving the survival rate of L. bulgaricus. Confocal laser scanning microscopy showed that BSGP-P generated a denser, softer and more homogenous surface appearance as well as showed the tendency to form more compact networks; had a weaker initial gel forming, increased and preserved the consistency of the yogurt during the storage. In conclusion, BSGPs in yogurt improved and preserved the textural properties, consistency, acidity and lactic acid bacteria.
The development of novel methods of producing transparent electrodes is important because of their ever-evolving applications and thus the additional parameters they must meet. In this work, we present a method of manufacturing semitransparent silver electrodes. This technique involves cracking the polyvinylpyrrolidone layer in the presence of a colloidal nanodispersion of zinc oxide. The resulting cracked polymer layer serves as the disposable mask for metal deposition. The whole procedure is valuable due to the fast and easy step of cracks formation caused by the elevated temperature and reduced pressure. The obtained electrodes have high transparency (82.4%) in a wide spectral range, which is only limited by the transparency of the applied substrate, and low resistivity (27.3 × 10-7 Ωm). The presence of unique patterns suggests new ideas for the applications of such electrodes, such as coding, security, and antiplagiarism protection.
Background/aim: Numerous studies have demonstrated an anti-cancer action of plant-derived polyphenols. Their action is mainly related to antioxidant, anti-inflammatory, immunomodulatory and inhibitory properties. It is expected that proper composition of nutrition factors with anti-cancer activity may prevent from cancer incidence or inhibit cancer progression. The aim of the study was to investigate the anti-cancer properties of a standardized composition of compounds: trans-resveratrol, quercetin, vitamin E and selenium (Neoplasmoxan, Vebiot) in a mouse model of CT26 colorectal carcinoma. Materials and methods: Colorectal carcinoma cells (CT26) were introduced subcutaneously (2×105/mouse) on the back of the mice. Neoplasmoxan suspension was administered intragastrically, daily, for 21 consecutive days. In collected tumors, the area occupied by tumor blood vessels and the number of immune cells; macrophages and CD8-positive cytotoxic T lymphocytes were evaluated. Results: It was observed that administration of Neoplasmoxan inhibits the growth of colorectal carcinoma in mice. Tumor volume after Neoplasmoxan administration was 40% smaller than in control groups. No overall toxicity of Neoplasmoxan was observed. The area of blood vessels in tumors of mice that received Neoplasmoxan was reduced by approximately 20%. The area occupied by macrophages increased about 60% compared to the control group. However, no increased number of CD8-positive cytotoxic T lymphocytes was observed in the group that received Neoplasmoxan. Conclusion: A tendency of Neoplasmoxan to inhibit the growth of colorectal carcinoma was recorded. It also seems that additional combination of the tested preparation with standard chemotherapy or radiotherapy should bring a synergistic therapeutic effect.
Mass spectrometry-based proteomics aims to study the proteome both qualitatively and quantitatively. A key step in proteomic analysis is sample preparation, which is crucial for reliable results. We investigated the effect of the composition of the homogenization buffer used to extract proteins from brain tissue on the yield of protein extraction and the number and type of extracted proteins. Three different types of buffers were compared—detergent-based buffer (DB), chaotropic agent-based buffer (CAB) and buffer without detergent and chaotropic agent (DFB). Based on label-free quantitative protein analysis, detergent buffer was identified as the most suitable for global proteomic profiling of brain tissue. It allows the most efficient extraction of membrane proteins, synaptic and synaptic membrane proteins along with ribosomal, mitochondrial and myelin sheath proteins, which are of particular interest in the field of neurodegenerative disorders research.
The core-shell structural design of low-dimensional nanomaterials and the synergistic effect of dielectric and magnetic loss have made a remarkable contribution to the electromagnetic wave absorbing performance. In this paper, two-dimensional graphene [email protected] polypyrrole/one-dimensional carbonyl iron fiber ([email protected]/CIF) composites with a core-shell structure were prepared by a facile in-situ chemical oxidative polymerization method, and their electromagnetic properties were systematically studied. It is indicated that when the mass ratio of [email protected] to [email protected]/CIF was 15 wt%, the optimal reflection loss reached -53.67 dB at 12.24 GHz with 2.56 GHz of effective absorption bandwidth (RL≤-10 dB), and the corresponding thickness was 2.13 mm. Additionally, the better impedance matching, large attenuation constant, and coupling effect of dielectric-magnetic loss played a combined role in the optimized absorption. Therefore, this study can complement the existing theories and provide guidance for the structural design of multi-dimensional hybrid functional materials with versatile properties and complementary advantages.
Sulfhemoglobinemia is an incurable disease caused by an overdose of sulfur-containing drugs with oxidizing properties. Its diagnosis remains hindered due to the similarity of symptoms to other pathological state – methemoglobinemia, as well as contradictory information on the structure and characteristics of sulfhemoglobin. Herein, we present sulfhemoglobinemia model on living functional human erythrocytes, designed to recreate processes which could take place in a patient body in order to complement missing information and highlight distinctiveness of two hemoglobin (Hb) adducts formed after interaction with sulfur donors. Employed techniques, UV–Vis absorption, Raman, Fourier transformed infrared (FT–IR) and electronic circular dichroism (ECD) spectroscopies, allowed to distinguish and characterize Hb adduct with sulfur atom bounded directly to the iron ion (HbFeIII–SH), and irreversibly connected to the porphyrin ring (SHb – sulfhemoglobin). Presented herein results provided also new evidence on formation of both these hemoglobin adducts inside functional erythrocytes under oxidative conditions and during sulfur-containing drug presence, what can be further translated into future physiological studies. Moreover, we found that sulfur attachment to the porphyrin ring altered Hb structure and lead to changes in protein packing inside RBCs, eventually. Interestingly, measurement of blood drop smear by Raman spectroscopy occurred the most accurate method to differentiate HbFeIII–SH and SHb, indicating potential of this technique in sulfhemoglobinemia diagnosis.
Transition metal dichalcogenides (TMDs), especially in two-dimensional (2D) form, exhibit many properties desirable for device applications. However, device performance can be hindered by the presence of defects. Here, we combine state of the art experimental and computational approaches to determine formation energies and charge transition levels of defects in bulk and 2D MX2 (M = Mo or W; X = S, Se, or Te). We perform deep level transient spectroscopy (DLTS) measurements of bulk TMDs. Simultaneously, we calculate formation energies and defect levels of all native point defects, which enable identification of levels observed in DLTS and extend our calculations to vacancies in 2D TMDs, for which DLTS is challenging. We find that reduction of dimensionality of TMDs to 2D has a significant impact on defect properties. This finding may explain differences in optical properties of 2D TMDs synthesized with different methods and lays foundation for future developments of more efficient TMD-based devices.
Most commercial zirconium alloys are obtained by melting methods and consist of α-Zr. The sintering of zirconium powders is carried out mainly by pressure methods, which is the reason for the appearance of higher stresses in the materials and the presence of the high-pressure ω-Zr phase. Sintered zirconium materials containing α-Zr, α-Zr + β–Zr + Nb and ω-Zr + α-Zr phases, with a relative density of approximately 98%, using the Spark Plasma Sintering method and the ultra-high pressure method were obtained. X-ray diffraction methods were used to determine the content of individual zirconium phases in the materials. Stresses were measured in alpha and omega zirconium phases by the sin² ψ diffraction method for all investigated materials. Hardness, tensile strength and elongation of materials were measured. The greatest elongation of 7.1% was found for sintered materials containing ω–Zr. The presence of the ω - Zr obtained under ultra-high pressure conditions does not significantly affect the stress level in ω Zr and in the α-Zr phase of the High Pressure – High Temperature sintered material. Tribological tests were carried out using the ball-on-disk method, with alumina as counter-samples. The research showed an adverse effect on the abrasive wear of the high-pressure omega Zr phase. The zirconium oxidation process and the separation of the oxide from the wear surface plays an important role in the abrasion of all sintered zirconium materials.
The post-annealing treatment condition has a great impact on the orientation and growth of perovskite phases. In this study, the formation of CH3NH3PbI3 films was controlled using different post-annealing processes, including a modified N, N-dimethylformamide (DMF) vapor treatment. Field-emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD) were used to characterize the microstructure of the perovskite films. An appropriate amount of DMF with a modified post-annealing setup dramatically improves the properties of the perovskite films, whereas an excess amount of DMF solvent leads to poor coverage and degraded films. The average grain size of the modified setup solvent-annealed perovskite film with 100 μL of DMF at 100 °C for 10 min reached ≈1.84 μm, almost five times larger than the mere 0.427 μm of the only thermally annealed at 100 °C for 10 min CH3NH3PbI3 film. The devices fabricated with the films with modified DMF vapor treatment showed improved photovoltaic performance, providing insight into the formation mechanism, and an effective method to improve the film quality of perovskite for photovoltaic application.
The preparation of composite materials is a promising methodology for concurrent optimization of electrical and thermal transport properties for improved thermoelectric (TE) performance. This study demonstrates how the acoustic impedance mismatch (AIM) and the work function of components decouple the TE parameters to achieve enhanced TE performance of the (1-z)Ge 0.87 Mn 0.05 Sb 0.08 Te-(z)WC composite. The simultaneous increase in the electrical conductivity (σ) and Seebeck coefficient (α) with WC (tungsten carbide) volume fraction (z) results in an enhanced power factor (α 2 σ) in the composite. The rise in σ is attributed to the creation of favorable current paths through the WC phase located between grains of Ge 0.87 Mn 0.05 Sb 0.08 Te, which leads to increased carrier mobility in the composite. Detailed analysis of the obtained electrical properties was performed via Kelvin probe force microscopy (work function measurement) and atomic force microscopy techniques (spatial current distribution map and current−voltage (I−V) characteristics), which are further supported by density functional theory (DFT) calculations. Furthermore, the difference in elastic properties (i.e., sound velocity) between Ge 0.87 Mn 0.05 Sb 0.08 Te and WC results in a high AIM, and hence, a large interface thermal resistance (R int) between the phases is achieved. The correlation between R int and the Kapitza radius depicts a reduced phonon thermal conductivity (κ ph) of the composite, which is explained using the Bruggeman asymmetrical model. Moreover, the decrease in κ ph is further validated by phonon dispersion calculations that indicate the decrease in phonon group velocity in the composite. The simultaneous effect of enhanced α 2 σ and reduced κ ph results in a maximum figure of merit (zT) of 1.93 at 773 K for (1-z)Ge 0.87 Mn 0.05 Sb 0.08 Te-(z)WC composite for z = 0.010. It results in an average thermoelectric figure of merit (zT av) of 1.02 for a temperature difference (ΔT) of 473 K. This study shows promise to achieve higher zT av across a wide range of composite materials.
The tunable control in the inorganic octahedral framework of hybrid perovskites offers potential applications in photovoltaics, solid-state lighting, and radiation detection. However, the implication of the structure and optoelectronic properties pose challenges due to competition between organic− inorganic coupling and intraoctahedral interactions. In this study, we combine X-ray absorption spectroscopy (XAS) and Raman analysis to interpret the angular-dependent behavior and anharmonicity of manganese-based single-crystal perovskites differing by a single methylene unit. The XAS spectra of manganese-based single-crystal perovskites with 2-phenethylamine (PEA) compared to 3-phenyl-1-propylamine (PPA) as organic cations unambiguously demonstrated a 180°intensity shift as a function of the incoming photon, suggesting a pronounced structural ligand variation. The out-of-plane polarization is found to be more prominent in L 2-edge than in L 3. In addition, an accompanying shoulder peak around 643 eV was attributed to the electron excitation from Mn 2p to 3d orbitals to form d 5 L states. A decrease in terms of field strength is prominently observed that infers a low crystal field splitting energy. Raman analysis of the two hybrid perovskites displays a notable difference in the respective translational modes at 84 and 87 cm −1 , which signifies the amplified anharmonicity due to extended chain length. Based on this phenomenological approach, a longer chain promotes a rather unique octahedral deformation than anharmonicity shift that is crucially important to decoupling the nature of the active units. This effort sheds some light to implement the orientational ordering toward an efficient charge transport of hybrid perovskite semiconductors.
In the present study, we characterized the secondary structure alterations of intact red blood cells (RBCs) cytosol with special attention to the sex-related alterations in 8- and 24-week-old female and male ApoE/LDLR-/- mice, compared to age-matched female and male C57BL/6J control animals. Results were obtained with previously established methodology based on Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Additionally, we evaluated 2,3-DPG levels in the RBCs and showed its potential link to the hemoglobin (Hb) secondary structure alterations. Considering Hb structure alterations probed by FTIR-ATR, the ratio of turns to α–helices in 8-week-old ApoE/LDLR-/- mice suggested more pronounced secondary structure alterations within the RBCs than in the age-matched control. Sex-related differences were observed solely in 24-week-old male ApoE/LDLR-/- mice, which showed statistically significant increase in the secondary structure alterations compared to 24-week-old female ApoE/LDLR-/- mice. Similar to the secondary structure alterations, no sex-related differences were observed in the levels of 2,3-DPG in RBCs, except for 24-week-old male ApoE/LDLR-/- mice, which showed significantly higher levels compared to the age-matched female ApoE/LDLR-/- mice. Considering the age-related alterations, we observed significant increases in the intracellular 2,3-DPG of RBCs with animals’ age in all studied groups, except for female ApoE/LDLR-/- mice, where a significant difference was not reported. This suggests the clear correlation between secondary structure of Hb alterations and 2,3-DPG levels for male and female murine RBC and proves a higher resistance of older female RBCs to the secondary structure changes with progression of atherosclerosis. Moreover, it may be concluded that higher 2,3-DPG levels in RBCs occurred in response to the secondary structure alterations of Hb in ApoE/LDLR-/- mice.
The paper presents the results of experimental investigations of the heat generation and microstructure evolution during the friction stir processing (FSP) of the SnSb11Cu6 alloy. The Triflute tool was used for modification; the process was carried out using two rotational speeds of the tool: 280 and 560 RPM and a constant linear speed of 355 mm/min. Microstructure studies were performed employing the techniques of light microscopy and scanning electron microscopy along with analysis of the chemical composition of micro-areas. Additionally, the phase composition was investigated by means of the X-ray diffraction method, and electron backscatter diffraction (EBSD) analysis and hardness testing were performed before and after FSP modification. Furthermore, measurements of the temperature directly on the modified surface by means of a thermal imaging camera and the temperature in the modified zone with a thermocouple system were performed. It was proved that using FSP to modify the SnSbCu alloy promotes refinement and homogenization of the microstructure, as well as improvement of the hardness. The hardness of the starting material was 24 HB, and after FSP, the hardness increased and amounted to, respectively, 25 and 27 HB after processing at 280 and 560 RPM. The microstructure in the stir zone is formed by the dynamic recrystallization (DRX) process and consists of almost equiaxed tin-rich matrix grains with a size of approx. 5–30 µm and fine particles of Cu6Sn5 and SnSb phases. The temperature distribution in the FSP zone is not uniform and changes in a gradient manner.
This work presents a nanocomposite-based humidity sensor based on zinc oxide nanostructured powder (ZNP) nanoparticles that achieves a maximum enhancement in the humidity sensing performance at room temperature due to the introduction of different amounts of reduced graphene oxide (rGO) loading from 0.5 wt.% to 2.0 wt.%. The rGO/ZNP (rZNP) nanocomposite-based humidity sensor was fabricated by using cellulose filter paper as a substrate and clear paper glue as a binder through a facile brush printing method. FESEM, EDS, XRD, HRTEM, XPS, and Raman spectroscopy were employed to investigate the properties of the ZNP and rZNP nanocomposites. The presence of an rZNP nanocomposite with quasi-spherical ZNP nanoparticles that are securely attached and anchored with rGO sheets was confirmed through HRTEM micrographs. Raman spectroscopy analyses confirm and validate the formation of hybrid nanostructures with the presence of distinctive bands related to ZNP and rGO. The presence of oxygen vacancy defects and oxygen-related chemical bonds on the surface of the rZNP nanocomposite, which yields enhanced sensor performance, is revealed by XPS analysis. The rZNP nanocomposite-based humidity sensor with 1.0 wt.% rGO loading (rZNP-1.0) had a maximum sensing response of 99.42% and exhibited the highest sensitivity towards humidity changes (172 or 29.2 MΩ/%RH), which was substantially better than the other tested samples.
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65 members
Izabela Sitkiewicz
  • Center for Population Diagnostics
Jakub Siednienko
  • Bioengineering Research Team
Patrick Groves
  • Analytics Area
Grzegorz Chodaczek
  • Biotechnology Area
Muhammad Danang Birowosuto
  • Photonics and Electronics area
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Stablowicka 147, Wrocław, Poland
Head of institution
Andrzej Dybczynski, phd, MBA
Website
port.org.pl