Technical University of Liberec

Fluorine magnetic resonance imaging (¹⁹F MRI) using polymer tracers overcomes limitations of conventional proton MRI by offering enhanced specificity. However, the lack of systematic comparisons among fluorinated polymers has hindered rational tracer design. In this study, we synthesized an extensive library of water-soluble fluorinated copolymers by varying ratios of hydrophilic and fluorinated monomers and evaluated their ¹⁹F MRI properties to identify key structure–property relationships. Optimizing the hydrophilicity of the non-fluorinated comonomer increased fluorine content without compromising water solubility, thereby enhancing the MRI signal. Factors such as chemical structure, molecular interactions, and magnetic relaxation times also significantly influenced tracer performance. The optimized copolymer, poly((N-(2,2,2-trifluoroethyl)acrylamide)60-stat-(N-(2-hydroxyethyl)acrylamide)40), exhibited unprecedented ¹⁹F MRI sensitivity with detection limits below 1 mg mL⁻¹, the highest reported to date. We demonstrated the tracer's potential through successful in vivo¹⁹F MRI visualization of solid tumors in mouse models, highlighting its promise for advanced biomedical imaging applications.

Road surface deicing is one of the main purposes of electrically conductive concrete. During the past few decades, using materials with multiple properties has gained increasing importance in technological developments and provided advantages compared to the traditional use of materials. Accordingly, electrically conductive components are widely searched to apply deicing on the pavement surface. This study primarily focused on the enhancement of conductive and mechanical properties of concrete by incorporating aluminum waste into the concrete mixture, in addition to addressing recycling and reusing of these materials. Aluminum waste namely aluminum chips and aluminum powder were utilized as conductive materials in concrete. Mechanical and conductive properties of seven mixtures that contain different proportions of the conductive materials were evaluated. The results indicate that mixture CH3P5 depicts the best mixture in terms of mechanical strengths and the lowest electrical resistivity followed by CH5P3. Mixtures CH3P5 and CH5P3 were selected for heating test due to their better performance during aforementioned tests on the mixtures containing conductive materials. Under 27 V, CH3P5 and CH5P3 surface temperature increased by 33.75 and 30.05 °C, respectively. Thus, satisfactory heating performance of waste aluminum as conductive material in concrete was confirmed.

This paper focuses on how to respond appropriately to the problem of the (non-)biodegradability of nanofibers and how the integration of ethics could help. First, the paper describes the experience of a bioengineering research team at the Technical University of Liberec in developing a technology for producing filtration materials during the COVID-19 pandemic and the project that was implemented to provide support for ethical decision-making in the field of research and development of nanotechnologies. The paper then looks into the limitations of the EU’s new Medical Device Regulation (2017/745) for the development and design of nanomaterials by focusing on the issue of the (non-)biodegradability of nanofibers. The main argument is that to advance sustainable nanotechnology practices it is essential to incorporate ethical frameworks VSD, which includes a more-than-human ethics, is proposed as suitable for addressing these issues.

Warp-knitted structures are widely used in many fields (medical textiles, household textiles, reinforcement for composites, …) owing to their special geometrical, mechanical, and physical properties. Their unique yet typical mechanical behavior is attributed to loops and underlaps in their structure. Herein, we investigated the relationship between warp-knitted-structure breaking strain and changes in their underlap lengths. We developed an original structural model of closed warp-knitted structures in a highly deformed state. Further, we defined two main stages during the straining of knitted structures. Finally, we verified the variation in the breaking strain of knitted structures with various underlap lengths using the developed model and experimental results.

This study presents a comprehensive optical analysis of titanium-doped sapphire (Ti:Sa) crystals, introducing two innovative measurement techniques to enhance the characterization of this material. The first method enables highly precise transmission measurements, facilitating the visualization of optical doping patterns across samples and providing accurate figure of merit (FoM) evaluations. This technique covers an area of 25 × 100 mm, enabling the creation of detailed optical property maps. The second method is specifically designed to identify stress and refractive index inhomogeneities using circular polarization, leveraging the birefringent properties of Ti:Sa material. Experimental validation was performed on three Ti:Sa samples with distinct defects, and their optical and structural properties were analyzed and compared. A central optical pattern, previously unreported, was observed in all samples. This pattern is hypothesized to originate from core formation during crystal growth. These findings provide new insights into the material's internal structure and hold significant implications for its optimization in optical applications.

Optical coating, an integral part of many optical systems, is prone to damage from environmental exposure and laser irradiation. This underscores the need for reliable and sensitive coating diagnostics. We introduce second harmonic generation (SHG) as a method for the sensitive detection of defects and inhomogeneities within optical thin films. We demonstrate the use of SHG on Si3N4 layers tested for their laser-induced damage threshold. The SHG mapping was compared with commonly used diagnostic techniques, including Nomarski microscopy, white light interferometry, and electron microscopy. Owing to its sensitivity to variations in local symmetry, SHG is able to discern minute alterations in material composition, mechanical stress, and interface structures. Therefore, SHG identified modifications in the tested layers, highly extending the damage recognized by standard methods. Furthermore, we demonstrate SHG's ability to enhance specific features by modulation of incidence angles and polarization modes. Based on these findings, we propose SHG as an ideal diagnostic tool for the early identification of laser-induced modifications in centrosymmetric thin films.

Aims This study evaluates the effectiveness of two standard sterilization methods on microorganisms in bentonite, which is proposed as a buffer around metal canisters containing long-lived radioactive waste. Bentonite, as a natural clay, contains microorganisms with enhanced resistance to harsh conditions and the ability to reactivate upon decompaction. Sterile controls are crucial in experiments estimating the impact of microorganisms on nuclear waste repositories. Yet, the effectiveness of common sterilization methods on bentonite microorganisms has not been fully evaluated. Methods and Results: Two methods were compared dry heat (nine cycles at 121°C for 4 hours) and gamma irradiation (10 to 140 kGy at 147 Gy·min−1). Molecular-genetic, microscopic, and cultivation techniques were used to assess sterilization. Heat sterilization did not eliminate heat-resistant microorganisms, such as Bacillus, Paenibacillus, and Terribacillus, from bentonite powder even after nine heat cycles. However, bentonite suspended in deionized water was sterile after four heat cycles. In contrast, gamma irradiation effectively reduced microbial survivability above a dose of 10 kGy, with the highest doses (100-140 kGy) potentially degrading DNA. Conclusions Gamma irradiation at 30 kGy effectively sterilized bentonite powder. The findings of our experiments emphasize the importance of using appropriate sterilization methods to maintain sterile controls in experiments that evaluate the microbial impacts in nuclear waste repositories. However, further assessment is needed to determine the effects of potential alterations induced by gamma radiation on bentonite properties.

Wire electrical discharge machining is an unconventional machining technology used in many industries. The machinability analysis of the newly-created materials is crucial for their future machinability with the given machining technology. For the machinability analysis, the influence of the machining parameters, namely pulse off time, gap voltage, discharge current, pulse on time and wire feed, was investigated in a planned experiment of 33 rounds. Both the cutting speed and roughness were analysed. The surface morphology of the machined pieces was examined with electron microscopy and the subsurface layer with cross-sectioning of the samples. A lamella was made for transmission electron microscopy to perform a detailed analysis of the chemical content. There was no sample made that would not result in cracks of 20–30 µm depth. These cracks let us assume that the service life of the parts machined in this way will be limited. Multi-criteria optimisation was used to find the optimum machining parameters, which allows the cutting speed to reach 3.2 mm/min and for Ra to reach 2.1 µm.

This research aims to provide valuable insights into the initial learning step — self-study materials formation. Nowadays, in a competitive environment, companies seek to identify the outstanding processes for the employee development. Therefore, this research identifies various factors and formats critical in the early phases of employee learning path. Utilizing a quantitative methodology, the study addresses two primary areas. The first is exploring technologies utilization within self-study materials and their helpfulness at the same time. The following area is focused on the motivational and engagement factors that positively influence learners' attitudes toward the development process. The research findings confirm that preparation of self-study materials is crucial for the subsequent learning path formation. The research is emphasizing the importance of clear learning objectives, interactive content, and a balanced use of diverse formats. Organizations can enhance their training programs by addressing of these key factors. Hence, current learning and development managers can practically utilize outputs from this research to lead more effective work-based learning processes within their organization.

Efficiently utilizing clean and renewable energies, green fuels and materials, and reuse-recycle processes are the cornerstones of a sustainable environment based on low-carbon circular economy. Joining modeling to research in the field of sustainability has been an accelerator towards a low-carbon world, which is discussed in this article. In beginning sections, factors affecting the sustainability of environment have been reviewed in terms of physical environment, constructions, energy, and green materials; however, it seems that green and low-carbon materials are entrenched in all four sectors. A combination of existing factors should be considered to design effective realistic models. In the following sections, by applying simulation practices in MATLAB 2019, a framework is presented due to the assessment of each industry based on environmental impacts (specifically carbon emission), a model is conveyed for energy scheduling in industries based on renewable resources with the application of Plan-Do-Check-Act (PDCA) model, and a policy-economy analysis system is developed for low-carbon manufacturing.

Pancreatic cancer remains one of the most challenging malignancies to treat due to its dense stromal microenvironment and resistance to conventional therapies. This study introduces a novel localized drug delivery system design to target residual cancer cells following surgery. Electrospun fibrous carriers were fabricated using needle-less electrospinning from polycaprolactone (PCL), silk fibroin (SF), and their blend. Among these, PCL carriers (average fiber diameter: 141 ± 28 nm) exhibited the highest and most sustained paclitaxel (PTX) release in vitro. Coating the PCL carrier with hyaluronic acid (HA) increased the fiber diameter to 535 ± 116 nm and modulated PTX release, shifting from an initial rapid release phase in uncoated carrier to a more gradual and sustained release over 120 hours. PTX-loaded HA-coated electrospun PCL carriers significantly reduced MiaPaCa cell viability, with only 13% viability at 96 hours compared to 22% for the non-coated carrier. This HA-coated electrospun PCL carrier offers a scalable and efficient solution for localized PTX delivery, providing sustained drug release, prolonged cytotoxic efficacy, and reduced off-target effects. Its industrial scaleability, combined with its potential for post-surgical pancreatic cancer management, presents an innovative approach to minimizing reliance on systemic chemotherapy and its associated toxicities. The use of needle-less NanospiderTM electrospinning technology further emphasizes its clinical potential, with future in vivo studies needed to confirm carrier’s safety, pharmacokinetics, and therapeutic benefits.

In the present research, an advanced silane-bonded polydopamine (PDA) coating through a simple, low-cost, and highly effective technique was employed to enhance the stability of copper-coated electromagnetic shielding fabrics. Coating the metalized nonwoven PET fabric with PDA can protect it from oxidation, mechanical forces, and extreme chemical conditions such as acid and alkali corrosion. The coated nonwoven fabric retained its excellent electromagnetic shielding effect even after machine- and handwashing cycles, showing average shielding effectiveness (SE) values above 41 dB for PDA@MEFTEX and Si-QAC/PDA@MEFTEX samples, and the average SE remained consistently above 39 dB under acidic and alkaline conditions. The PDA-coated MEFTEX did not significantly increase the surface and volume resistivities and exhibited excellent thermal insulation properties. In addition, silane-bonded PDA coating increased the softness, acted as a barrier, and provided a perfect interface that inhibits the penetration of corrosive ions from the surroundings. This outcome further highlights the promising impact of the novel coating, serving as protective coverage for metalized nonwoven fabric and providing good physical and thermal properties. This method can effectively protect electromagnetic shielding cloth, prolong the use time of shielding material, and expand its scope of application.

Accurate and efficient diagnosis of COVID-19 remains a significant challenge due to the limitations of current detection methods, such as blood tests and chest scans, which can be time-consuming and error-prone. This study aims to compare the performance of basic and hybrid data mining algorithms in diagnosing COVID-19, using blood test results and clinical information to identify the most effective approach. A dataset of 200 records from suspected and infected COVID-19 patients, with 23 characteristics and one diagnostic class, was analysed. Nine data mining algorithms were tested: four basic algorithms (Naive Bayes, Support Vector Machine, Decision Tree, K-Nearest Neighbor) and five hybrid algorithms (Random Forest, AdaBoost, Majority Voting, XGBoost, Bagging). The study also integrated Response Surface Methodology (RSM) and Adaptive-Network-based Fuzzy Inference System (ANFIS) to enhance model performance. The Bagging algorithm demonstrated superior performance with an accuracy of 88%, sensitivity of 74%, and F-criterion of 78%. The integration of RSM and ANFIS further showed that a smart model could be developed for efficient pandemic crisis management, achieving up to 100% accuracy when considering key factors like AST, Albumin, and CRP. The findings suggest that Bagging and hybrid data mining algorithms can significantly improve COVID-19 detection, reducing time and errors in identifying exposed individuals. The study highlights the potential of combining machine learning techniques with RSM-ANFIS models for effective pandemic management and decision-making in medical settings.

The ornamental pet trade has emerged as one of the most important pathways for the introduction of non‐native aquatic species. In the last two decades, freshwater crayfish have become a popular ornamental group, with numerous non‐native populations established through this way, including some populations of the North American red swamp crayfish Procambarus clarkii (Girard, 1852). Whilst the introduction routes of aquaculture‐derived populations have been identified through molecular methods and historical documents, obtaining traceability in the pet trade market is often more challenging. We analysed 283 pet‐traded and feral P. clarkii individuals, originating from Europe and Southeast Asia, for variation of a fragment of the mitochondrial gene for cytochrome c oxidase subunit I (COI) to determine the genetic variation amongst 11 pet shops in various countries, outdoor aquaculture in Indonesia and 27 established feral populations in Europe likely originating from releases of ornamental animals. We found 13 haplotypes, four of which had not been detected in P. clarkii before. Overall, higher haplotype diversity was found in established feral populations (Hd = 0.555) and outdoor aquaculture (Hd = 0.667) compared to pet shops (Hd = 0.141). We observed up to three haplotypes shared between the Asian pet trade and Europe. Whilst one of them appeared in a pet shop in Indonesia and open waters in Hungary, another was observed in the pet trade in Cambodia, outdoor aquaculture in Indonesia and in the stock of European wholesalers. The third was the most common haplotype and provided little information regarding the species' introduction routes. Additionally, one haplotype present in the European pet trade was commonly found in European waters. Particularly noteworthy was the high haplotype variability of Hungarian populations collected in the metropolitan area of Budapest, which is considered a European hotspot of ornamental crayfish introductions. The findings of our study support the low haplotype diversity in pet shops, likely stemming from a limited number of founders of most P. clarkii ornamental stocks. In contrast, higher genetic variability in feral populations may be due to recurrent introduction events from different sources. Furthermore, the results support the hypothesis that the crayfish occurring in the European pet trade originate from the Asian ornamental trade rather than from the North American native range of P. clarkii . Legally binding regulations on listing non‐native species do not seem to curb the importation of ornamental non‐native species. However, the implementation of molecular methods conducted at border controls (by veterinarians) and post‐border (by wholesalers and retailers) in cooperation with research institutions can efficiently serve as preventive measures to halt species importations. We emphasise using molecular analyses for both species identification and tracking introduction routes of biological invasions.

Silicon-based solar cells dominate the photovoltaic market, with commercial monocrystalline silicon cells reaching efficiencies as high as 27.3% by May 2024. An alternative to monocrystalline silicon solar cells is polycrystalline solar cells. Despite their lower efficiency (record: 23.81%), their manufacturing process is simpler and cheaper, and their energy conversion efficiency is less sensitive to temperature changes. However, limitations persist in optical and electrical losses, particularly underutilizing ultraviolet (UV) radiation due to silicon’s bandgap. To address these issues, the application of down-converting materials like zinc oxide (ZnO) quantum dots (QDs) has gained attention. ZnO QDs absorb high-energy UV light and re-emit it in the visible spectrum, optimizing the portion of solar energy usable by silicon cells. This study explores the synthesis of ZnO QDs using a sol–gel method, followed by their application on polycrystalline silicon solar cells. Experimental results indicated an increase in short-circuit current and overall efficiency, with the efficiency rising from 18.67% to a maximum of 19.05% when ZnO QDs were deposited from a 5 mg/mL solution. These findings suggest that ZnO QDs could significantly enhance solar energy conversion efficiency by utilizing portions of the solar spectrum that would otherwise be wasted.

Pulsed field ablation uses irreversible electroporation to interrupt cellular membranes and induce myocyte apoptosis. Reversible electroporation has been used in other specialties, but its utility in cardiac ablation is unknown. Here, a 69-year-old woman undergoing repeat ablation for atypical atrial flutter presented with extensive scar after cardiac surgery (including MAZE) and previous ablation, leading to a macro re-entry circuit. To minimize superfluous lesions and further arrhythmia, we used a single pulse confirming the isthmus location, with cessation of the arrhythmia. As a conclusion, reversible electroporation may be used to test areas of interest prior to irreversible lesion creation.

This study employs electrospinning to fabricate and characterize composite nanofibrous layers composed of polyamide 6 and titanium dioxide (TiO₂) particles. Polyamide 6 solutions were prepared with varying TiO₂ concentrations (5, 10, 15, 20, 30, 40, 50, 60, 70, and 80 wt%) to investigate the impact of filler content on the spinning process and the resulting nanofiber morphology. The conductivity and viscosity of these solutions were measured to assess their spinnability. The fabricated nanofibrous layers were characterized to determine the distribution of TiO₂ particles and their influence on the overall morphology. Additionally, the wetting behavior and ultraviolet radiation (UV) absorption properties of the layers were evaluated. The results indicate that nanofibrous layers containing 50% TiO₂ exhibit the highest UV absorption potential, making them promising candidates for further applications.

Background Sulodexide is a glycosaminoglycan-based drug prescribed to patients with angiopathy. We performed a pilot study to investigate whether sulodexide positively modulates the endothelial glycocalyx (EG) layer and the microcirculation in a porcine model of EG enzymatic damage. The EG is a sugar-based endothelial lining that is involved in the physiology of the capillary wall and the pathogenesis of many diseases. Methods EG damage was induced in eight piglets by hyaluronidase III and heparanase I given intravenously. Four animals received sulodexide 600 IU intravenously before the enzymes and four animals after the enzymes were administered. Four animals constituted a control group. Sublingual microcirculation by side-stream dark field imaging and plasmatic concentration of syndecan-1 by ELISA were measured at baseline, 20 min after intervention, and at the 40th, and 60th minute onwards. The statistics were performed with a one-way ANOVA test with Turkey's correction for multiple comparisons testing. Timepoint comparison was performed by Student t-test or Mann-Whitney test. Results At baseline, there were no statistically significant differences between the animal groups. After the intervention, the levels of syndecan-1 were significantly lower in the control group. While there were no differences between the two intervention groups. The sublingual microcirculation analysis showed that the DeBacker score was significantly higher in the control group. At 60 min, there was also a statistically significant difference in DeBacker score between the groups (8.1 ± 1.6 mm ⁻¹ in the group with enzymes given first and 11 ± 0.92 mm ⁻¹ in the group with sulodexide given first, p = 0.03). The analysis of the proportion of perused vessels did not show any statistically significant differences. Conclusion The results of the study demonstrated a working model of EG damage but no specific action of sulodexide on EG modulation. In the sublingual microcirculation analysis, the sulodexide reduced the fall in absolute tissue perfusion in 60 min.

Background The ischemia-reperfusion injury (IRI) is unavoidable in vascular surgery. Damage to the microcirculation and endothelial glycocalyx might set up a shock with loss of circulatory coherence and organ failure. Sulodexide may help to protect endothelial glycocalyx and alleviate the ischemia-reperfusion injury. Methods Twenty female piglets underwent surgery with a 30-min-long suprarenal aortic clamp, followed by two hours of reperfusion. Ten piglets received sulodexide before the clamp, and 10 received normal saline. Blood and urine samples were taken at baseline and in 20-min intervals until the 120 th minute to analyze the serum syndecan-1, E-selectin, and thrombomodulin. Albumin and glycosaminoglycans were examined in the urine. The kidney biopsies before and after the protocol were examined by light microscopy with hematoxylin-eosin staining. The sublingual microcirculation was recorded by side-stream dark field imaging at the time as blood and urine. Results Based on the 2-way ANOVA testing, there was no statistically significant difference in the parameters of sublingual microcirculation. Serum markers of endothelial cell activation and damage (E-selectin and thrombomodulin) did not show any statistically significant difference either. Syndecan-1, a marker of glycocalyx damage, showed statistically significantly higher values based on the 2-way ANOVA testing (p < 0.0001) with the highest difference in the 80 th minute: 7.8 (3.9–44) ng/mL in the control group and 1.8 (0.67–2.8) ng/mL in the sulodexide group. In the urine, the albuminuria was higher in the control group, although not statistically significant. Glycosaminoglycans were statistically significantly higher in the sulodexide group based on the mixed-effect analysis due to the intervention itself. Histological analysis of the renal biopsies showed necrosis in both groups after reperfusion. Conclusion Administering sulodexide significantly reduced the level of endothelial markers of IRI. The study results support further research into using preemptive administration of sulodexide to modulate IRI in clinical medicine.