Publikační činnost Centra nanotechnologií / Publications of Nanotechnology Centre (9360)

Permanent URI for this collectionhttp://hdl.handle.net/10084/64663

Kolekce obsahuje bibliografické záznamy publikační činnosti (článků) akademických pracovníků Centra nanotechnologií-CNT (9360) v časopisech registrovaných ve Web of Science od roku 2003 po současnost.
Do kolekce jsou zařazeny:
a) publikace, u nichž je v originálních dokumentech jako působiště autora (adresa) uvedena Vysoká škola báňská-Technická univerzita Ostrava (VŠB-TUO),
b) publikace, u nichž v originálních dokumentech není v adrese VŠB-TUO uvedena, ale autoři prokazatelně v době jejich zpracování a uveřejnění působili na VŠB-TUO.

Bibliografické záznamy byly původně vytvořeny v kolekci Publikační činnost akademických pracovníků VŠB-TUO, která sleduje publikování akademických pracovníků od roku 1990.

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Now showing 1 - 20 out of 810 results

Cross-coupling reactions with nickel, visible light, and tert-butylamine as a bifunctional additive
(American Chemical Society, 2024) Düker, Jonas; Philipp, Maximilian; Lentner, Thomas; Cadge, Jamie A.; Lavarda, João E.A.; Gschwind, Ruth M.; Sigman, Matthew S.; Ghosh, Indrajit; König, Burkhard
Transition metal catalysis is crucial for the synthesis of complex molecules, with ligands and bases playing a pivotal role in optimizing cross-coupling reactions. Despite advancements in ligand design and base selection, achieving effective synergy between these components remains challenging. We present here a general approach to nickel-catalyzed photoredox reactions employing tert-butylamine as a cost-effective bifunctional additive, acting as the base and ligand. This method proves effective for C-O and C-N bond-forming reactions with a diverse array of nucleophiles, including phenols, aliphatic alcohols, anilines, sulfonamides, sulfoximines, and imines. Notably, the protocol demonstrates significant applicability in biomolecule derivatization and facilitates sequential one-pot functionalizations. Spectroscopic investigations revealed the robustness of the dynamic catalytic system, while elucidation of structure-reactivity relationships demonstrated how computed molecular properties of both the nucleophile and electrophile correlated to reaction performance, providing a foundation for effective reaction outcome prediction.
Overcoming nanosilver resistance: Resensitizing bacteria and targeting evolutionary mechanisms
(American Chemical Society, 2024) Sun, Rui; Cui, Yueting; Wu, Yining; Gao, Meng; Xue, Shiyuan; Li, Ruibin; Zbořil, Radek; Zhang, Chengdong
The rapid spread of antimicrobial resistance poses a critical threat to global health and the environment. Antimicrobial nanomaterials, including silver nanoparticles (AgNPs), are being explored as innovative solutions; however, the emergence of nanoresistance challenges their effectiveness. Understanding resistance mechanisms is essential for developing antievolutionary strategies. AgNPs exhibit diverse resistance mechanisms, and our findings reveal a dynamic transition between these mechanisms: from flagellin-mediated AgNP precipitation (state I) to activation of the copper efflux pump (CusCFBA) system (state II). We designed targeted physicochemical interventions to counteract these mechanisms. Energy supply blocking was effective for state I, while for state II, neutralizing intracellular acidic pH significantly reduced resistance. These strategies reduced nanoresistance/tolerance by up to 10,000-fold. Additionally, resistance evolution can be completely halted by disrupting the energy supply using carbonyl cyanide 3-chlorophenylhydrazone and overactivating sigma E, one of the key envelope stress regulators that govern resistance transitions. Our findings provide practical strategies to overcome nanoresistance, offering a groundbreaking approach to enhance nanoantimicrobials' efficacy in medical therapies and combat resistance evolution.
Appropriate agro-environmental strategy for ZnO-nanoparticle foliar application on soybean
(Polskie Towarzystwo Gleboznawcze, 2024) Ernst, Dávid; Kolenčík, Marek; Straka, Viktor; Šebesta, Martin; Ďurišová, Ľuba; Tomovičová, Lenka; Kratošová, Gabriela; Ravza, Ivan; Žitniak Čurná, Veronika; Černý, Ivan; Qian, Yu; Gažo, Ján; Ducsay, Ladislav; Polláková, Nora; Juriga, Martin
Although the nanoparticle (NP) utilization in agronomy is currently orientated to intensify crop yield, the potential negative effects on soil and plant reproductive organs, including effects on pollen are largely absent in the literature. For this reason, our study was set to evaluate the impact of ZnO nanoparticles (ZnO-NPs) on the selective properties of Fluvisol, on the direct microbial activity and zinc (Zn) phytoavailability, and crop yield after their foliar application on soybean [ Glycine max (L.) Merril] under field conditions. Additionally, the potential hazardous impact to plant reproductive structures was evaluated, focusing on the agronomically and environmentally sensitive biomarker - pollen viability. The soil biological activity was evaluated through microbial respiration while Zn phytoavailability was determined using reaction agents with nutrients analysis conducted through flame atomic absorption spectroscopy (F-AAS). Pollen viability was evaluated using the iodine potassium iodide (IPI) test. The experiments were carried out at an experimental site of the Faculty of Agrobiology and Food Resources (FAFR) at the Slovak University of Agriculture (SUA) in Nitra, located in Central Europe, during the 2023 vegetation season. Depending on increasing concentrations of ZnO-NPs through order of 1.4, 14, and 140 mg L-1, revealed no harmful effect on soil microbial activity or hazardous Zn accumulation in the context of its Fluvisol-phytoavailable distribution compared to NPs-free control. A positive impact on soybean pollen viability was observed at all applied ZnO-NP concentrations compared to the NP-free control. The highest pollen viability, reaching up to 97.04%, was achieved at a concentration of 1.4 mg L-1, and, subsequently, it slightly decreased with increasing concentrations of ZnO-NPs. Moreover, the application of ZnO-NPs had a positive impact on soybean weight of thousand seeds and seed yield, where it's the highest concentration was the most effective. Thus, our results directly demonstrate the positive efficiency on selective properties of soil and reproductive structure - pollen, where ZnO-NP spray application acted positively and stimulatingly. Additionally, ZnO-NPs had positive impact on weight of thousand seeds (TSW) and seed yield. Therefore, the use of nanoparticles in foliar applications could be considered as kind of novelty in precision and sustainable agriculture.
Densely carboxylated graphene for synthesis of high-performing NASICON cathodes for Na-ion batteries
(American Chemical Society, 2026) Obraztsov, Ievgen; Cymann-Sachajdak, Anita; Bruniecka, Kamila; Madajski, Piotr; Šedajová, Veronika; Trykowski, Grzegorz; Bakandritsos, Aristides; Wilamowska-Zawłocka, Monika
Sodium-ion batteries are emerging as a promising alternative to lithium-ion technology due to the abundance and low cost of sodium. Among the cathode candidates, Na3V2(PO4)3 (NVP) with a NASICON framework and its analogues offer a high operating voltage and excellent structural stability. However, their practical use is limited by poor electronic conductivity, a low active material fraction, and trade-offs in terms of morphology and tap density. Here, we report a simple synthesis strategy that employs densely carboxylated graphene, graphene acid (GA), as a multifunctional additive. GA acts simultaneously as a chelating agent, pH regulator, and in situ-formed carbon shell prior to calcination. GA allows the efficient reduction of V5+ to electrochemically active V3+, phase-pure NVP formation, and the growth of a thin, conformal carbon shell strongly anchored to NVP particles. The resulting electrodes contain 85 wt % active material while maintaining outstanding charge-transfer kinetics. The optimized NVP@GA cathode delivers an excellent rate performance up to 15 A gEM -1 (151 C), retaining 65.4% of the theoretical capacity of NVP, and stable cycling. This approach provides a versatile route for tailoring NASICON cathodes and can be extended to other phosphate-based systems for high-power sodium-ion batteries.
Enhancing early osteogenic differentiation on Ti6Al4V implants via MAO coatings doped with strontium and calcium
(Elsevier, 2026) Gabor, Roman; Doubková, Martina; Cvrček, Ladislav; Filová, Elena; Malic, Marina; Mašek, Karel; Hlinka, Josef; Martynková, Gražyna Simha; Walter, Jan; Večeř, Marek; Seidlerová, Jana; Tokarčíková, Michaela; Bačáková, Lucie
Titanium alloys such as Ti6Al4V are widely used in orthopaedic implants due to their excellent mechanical and corrosion-resistant properties. However, insufficient early-stage osseointegration remains a critical challenge, often leading to implant loosening and failure. To overcome this issue, bone implant design and surface modification increasingly focus on incorporating bioactive elements. This study explores the enhancement of osseointegration through micro-arc oxidation (MAO) surface modification of Ti6Al4V, incorporating bioactive strontium (Sr) and calcium (Ca) ions. Two surface pretreatments - polishing (P) or shot-blasting (B) - were applied prior to MAO to generate coatings with distinct topographies and compositions: TAV(P), TAV(P)-Sr, TAV (P)-Sr-Ca, TAV(B), TAV(B)-Sr, and TAV(B)-Sr-Ca. Surface characterization of the resulting oxide layers confirmed the incorporation of Sr, Ca, and phosphate ions, with Sr releasing continuously over 60 days. Wear resistance analysis revealed the highest coefficient of friction for the TAV(P)-Sr coatings and the lowest values for TAV(B)-Sr. Surface modification by blasting led to reduced corrosion resistance in the TAV(B), TAV(B)-Sr, and TAV(B)-Sr-Ca samples. Nevertheless, enhanced corrosion resistance was observed in all samples modified with Sr and Sr+Ca. In vitro analyses using human bone marrow-derived mesenchymal stromal cells (hBMSCs) demonstrated excellent biocompatibility of all coatings. Notably, Sr-doped and especially Sr-Ca-doped surfaces significantly enhanced early osteogenic differentiation, as evidenced by increased alkaline phosphatase activity and type I collagen deposition. These findings highlight the synergistic effects of surface topography and Sr-Ca ion doping in promoting early-stage osseointegration, offering a promising strategy for improving the performance of titanium-based bone implants, particularly in patients with compromised bone healing.
Oxidative pyrolysis of alkali lignin using nitrogen functionalized graphene oxide-cerium oxide nanocatalysts: Mechanistic insights thorough density functional theory
(Elsevier, 2025) Kumar, Shivam; Kumar, Pankaj; Kumar, Navneet; Park, Jinsub; Srivastava, Vimal Chandra
In this study, a functionalized graphene oxide-cerium oxide nanocatalysts (FGCe) with varying graphene oxide (GO) contents were prepared using an in-situ reflux method. The prepared nanocatalysts showcased improvement in the crystallinity and BET surface area values with increasing GO contents. The efficacies of prepared catalysts were investigated towards oxidative pyrolysis of alkali lignin in an ethanol-water system. Among various nanocatalyst samples, the best lignin conversion (93 %) and bio-oil yield (86 %) were achieved using 50 mg FGCe nanocatalyst (0.5 wt% GO) at 423 K and 60 min. GC-MS and 1HNMR analyses were used to identify significant lignin conversion products, including 2-pentanone-4-hydroxy-4-methyl, 2-methoxyphenol, nonylcyclopropane, vanillin, apocynin, homovanollic acid, and benzoic acid. Kinetic studies revealed that the activation energy for lignin conversion was 24.36 kJ/mol at 423 K. Mechanistic investigations by density functional theory analysis revealed that the lignin breakdown occurred at oxygen bonds producing aromatic.
New approach to assessing nanofiber-based air filters efficiency across variable airflow velocities
(Elsevier, 2025) Dvorský, Richard; Bednář, Jiří; Vilamová, Zuzana; Šimonová, Zuzana; Svoboda, Ladislav
Filtration is a fundamental method in aerosol science for separating unwanted particles, mainly through air filters. Since the onset of the SARS-CoV-2 pandemic in 2019, there has been an increased demand for high- efficiency, low-cost nanofiber-based respirators capable of filtering particles within the size range of viruses and bacteria. The quality factor QF is the critical parameter for evaluating these respirators' practical effectiveness. QF integrates filtration efficiency with a tolerable pressure drop for the respiratory process. Typically, this pressure drop is reported as a function of the flow rate for a given respirator. However, the physical mechanism of filtration is governed by the mean frontal airflow velocity, which depends not only on the flow rate but also on the membrane area, a parameter often unknown in practical applications. The aerosol flow rate influences filtration efficiency and pressure drop through the membrane, yet a comprehensive physical description of this process has been lacking. Therefore, we developed a mathematical-physical model for filtration using a nanofibrous membrane that accounts for all relevant physical mechanisms. This model provides a more accurate definition of the quality factor. Our findings indicate that filtration efficiency does not reach 100 %, even at near-zero air velocities, and that efficiency approaches an asymptotic plateau at high velocities. When fitted to experimental data from various filters using a three-parameters approach, the model's predictions show strong agreement, particularly within the central region of the uncertainty band.
Fibrous PVDF membranes modified by anchored g-C3N4@GO composite with enhanced photocatalytic activity
(Elsevier, 2024) Vilamová, Zuzana; Czernek, Pavel; Zágora, Jakub; Svoboda, Ladislav; Bednář, Jiří; Šimonová, Zuzana; Plachá, Daniela; Dvorský, Richard
Recently, the development of fibrous membranes for pollutant filtration from air or water has been a topic of great interest. However, these filters' high and rapid fouling has limited their use. In response, we have prepared photocatalytic active membranes that harness the synergic effect between graphene oxide (GO) and graphitic carbon nitride (g-C3N4). The resulting composite demonstrated the highest photocatalytic activity (k(obs) = 88 x 10(-3) min(-1)). This g-C3N4@GO composite was then carefully deposited on/in an electrospun polyvinyl difluoride (PVDF) fibrous membrane. The reproducible results of the chemical bonding of the composite to the PVDF matrix were evident during photocatalytic experiments after ten Rhodamine B (Rh B) photocatalytic degradation cycles. Importantly, the fiber structure analysis post-reaction did not reveal any fiber cracks or void formation defects, indicating the excellent chemical stability of the PVDF fibrous matrix. This research offers a promising, sustainable, eco-friendly, and efficient solution for removing pollutants from different environments, inspiring further exploration and development in this field.
Improved ammonia synthesis and energy output from zinc-nitrate batteries by spin-state regulation in perovskite oxides
(American Chemical Society, 2025) Guo, Hele; Zhou, Yazhou; Chu, Kaibin; Cao, Xueying; Qin, Jingjing; Zhang, Nan; Roeffaers, Maarten B. J.; Zbořil, Radek; Hofkens, Johan; Müllen, Klaus; Lai, Feili; Liu, Tianxi
Electrocatalytic nitrate reduction to ammonia (eNRA) is a promising route toward environmental sustainability and clean energy. However, its efficiency is often limited by the slow conversion of intermediates due to spin-forbidden processes. Here, we introduce a novel A-site high-entropy strategy to develop a new perovskite oxide (La0.2Pr0.2Nd0.2Ba0.2Sr0.2)CoO3-delta (LPNBSC) for eNRA. The LPNBSC possesses a higher concentration of high-spin (HS) cobalt-active centers, resulting from an increased concentration of [CoO5] structural motifs compared to conventional LaCoO3. Consequently, this material exhibits a significantly improved electrocatalytic performance toward ammonia (NH3) production, resulting in a 3-fold increase in yield rate (129 mu mol h-1 mgcat. -1) and a 2-fold increase in Faradaic efficiency (FE, 76%) compared to LaCoO3 at the optimal potential. Furthermore, the LPNBSC-based Zn-nitrate battery reaches a maximum FE of 82% and an NH3 yield rate of 57 mu mol h-1 cm-2. Density functional theory calculations reveal that A-site high-entropy management in perovskites facilitates nitrate activation and potentially optimizes the thermodynamic rate-determining step of the eNRA process, namely, *HNO3 + H+ + e- -> *NO2 + H2O. This work presents an efficient concept for modulating the spin state of the B-site metal in perovskites and offers valuable insights for the design of high-performance eNRA catalysts.
Multi-molecular logic framework based on Morse code, ASCII logic, and Beale's cipher for advanced crypto-steganography
(Wiley, 2026) Mattath, Mohamed Nabeel; Lu, Yingying; Parambil, Ajith Manayil; Gao, Yan; Yao, Tian-Ming; Li, Jing-Jing; Zang, Rui-Min; Hu, Song; Shi, Shuo
Molecular information coding (MIC) involves biomolecules to encrypt and transmit messages, remains in its early stages of development. This work presents a versatile molecular integration framework and a proof-of-concept multi-level security system that combines Morse code, ASCII code, and Beale's cipher through molecular logic computing, using a molecular dye-oligonucleotide platform (single-stranded DNA, duplex DNA, stem-loop, and G-quadruplex (G-4) structures). This study demonstrates the integration of nanotechnology with crypto-steganographic methods to visualize and decipher codes, embedding elementary logic operations into molecular signal transduction. Additionally, a graphical user interface (GUI) is developed for classifying elementary logic gates using a decision tree algorithm, providing researchers with an accessible tool for rapid prediction. The Morse code-mediated strategy enables static key generation using dots, dashes, and intervals, and dynamic key generation through a polyalphabetic cipher framework. In parallel, ASCII-based logic gate operations facilitate multi-key decryption of decimal values to recover hidden information. Furthermore, a multilayered hybrid cryptographic technique combining Beale's cipher with Morse code implemented via a pangramic codebook, establishes an exceptionally resistant system against brute-force attacks. These methods provide insights into the evolution of communication and highlight the importance of encryption without relying on highly complex materials or sophisticated instruments.
Development of iron-based single atom materials for general and efficient synthesis of amines
(Wiley, 2024) Ma, Zhuang; Kuloor, Chakreshwara; Kreyenschulte, Carsten; Bartling, Stephan; Malina, Ondřej; Haumann, Michael; Menezes, Prashanth W.; Zbořil, Radek; Beller, Matthias; Jagadeesh, Rajenahally V.
Earth abundant metal-based heterogeneous catalysts with highly active and at the same time stable isolated metal sites constitute a key factor for the advancement of sustainable and cost-effective chemical synthesis. In particular, the development of more practical, and durable iron-based materials is of central interest for organic synthesis, especially for the preparation of chemical products related to life science applications. Here, we report the preparation of Fe-single atom catalysts (Fe-SACs) entrapped in N-doped mesoporous carbon support with unprecedented potential in the preparation of different kinds of amines, which represent privileged class of organic compounds and find increasing application in daily life. The optimal Fe-SACs allow for the reductive amination of a broad range of aldehydes and ketones with ammonia and amines to produce diverse primary, secondary, and tertiary amines including N-methylated products as well as drugs, agrochemicals, and other biomolecules (amino acid esters and amides) utilizing green hydrogen.
Real time tracking of nanoconfined water-assisted ion transfer in functionalized graphene derivatives supercapacitor electrodes
(Wiley, 2024) Padinjareveetil, Akshay Kumar K.; Pykal, Martin; Bakandritsos, Aristides; Zbořil, Radek; Otyepka, Michal; Pumera, Martin
Water molecules confined in nanoscale spaces of 2D graphene layers have fascinated researchers worldwide for the past several years, especially in the context of energy storage applications. The water molecules exchanged along with ions during the electrochemical process can aid in wetting and stabilizing the layered materials resulting in an anomalous enhancement in the performance of supercapacitor electrodes. Engineering of 2D carbon electrode materials with various functionalities (oxygen (& horbar;O), fluorine (& horbar;F), nitrile (& horbar;C equivalent to N), carboxylic (& horbar;COOH), carbonyl (& horbar;C & boxH;O), nitrogen (& horbar;N)) can alter the ion/water organization in graphene derivatives, and eventually their inherent ion storage ability. Thus, in the current study, a comparative set of functionalized graphene derivatives-fluorine-doped cyanographene (G-F-CN), cyanographene (G-CN), graphene acid (G-COOH), oxidized graphene acid (G-COOH (O)) and nitrogen superdoped graphene (G-N) is systematically evaluated toward charge storage in various aqueous-based electrolyte systems. Differences in functionalization on graphene derivatives influence the electrochemical properties, and the real-time mass exchange during the electrochemical process is monitored by electrochemical quartz crystal microbalance (EQCM). Electrogravimetric assessment revealed that oxidized 2D acid derivatives (G-COOH (O)) are shown to exhibit high ion storage performance along with maximum water transfer during the electrochemical process. The complex understanding of the processes gained during supercapacitor electrode charging in aqueous electrolytes paves the way toward the rational utilization of graphene derivatives in forefront energy storage applications.
Thermodynamic and multi-step kinetic analysis of slow pyrolysis of natural rubber-silanised cellulose composites with 30-55 phr filler content
(Elsevier, 2026) Dobrovská, Jana; Skalková, Petra; Iudina, Elizaveta; Holešová, Sylva; Kawuloková, Monika; Janík, Róbert
Pyrolysis is a promising thermochemical process for waste reduction and energy recovery. Natural rubber (NR) composites filled with 30, 45, and 55 phr silanised cellulose (CELS) were prepared and characterised by SEM and FTIR techniques. Thermogravimetric curves for heating rates of 2, 4, 6, 8, 10, and 20 °C·min−1 were measured in an inert gas. Kinetic parameters were determined by isoconversional kinetic analysis using the Friedman model-free method and a model-based method. By applying the generalised master plot method, it was found that the pyrolysis process follows an autocatalytic mechanism involving two kinetically independent, parallel pathways, each pathway consisting of two sequential steps. The results show that silanisation of cellulose has a positive effect on composite thermal stability, but only up to a specific content of CELS. At high loadings, the resulting silica-rich ash can act as a solid acid catalyst, accelerating secondary cracking reactions during pyrolysis. Innovative approaches for determining the formal thermodynamic parameters have been presented. The first method is based on the Eyring equation and the knowledge of Eα = f(α) and Aα = f(α) from the model-free method, providing the thermodynamic parameters as a function of the entire conversion range, α. The second method is based on the results of model-based kinetic analysis. The method makes it possible to determine these parameters for individual steps of a multi-step model and, thus, to compare the energy demand, spontaneity, and change in disorder of the system in the transition state for these steps.
Nickel-catalyzed reductive hydrolysis of nitriles to alcohols
(Wiley, 2025) Kuloor, Chakreshwara; Goyal, Vishakha; Zbořil, Radek; Beller, Mathias; Jagadeesh, Rajenahally V.
Nitriles are an abundant class of compounds that are widely used as versatile feedstocks to produce variouschemicals including pharmaceuticals, and agrochemicals as well as materials. Here we report Ni-catalyzed reductivehydrolysis of nitriles to alcohols in the presence of molecular hydrogen. This conversion likely occurs in a dominoreaction sequence that first involves the hydrogenation of nitrile to primary imine, then the hydrolysis of imine, andsubsequent deamination to the aldehyde, which is finally hydrogenated to the desired alcohol. Crucial for this reductivehydrolysis process is the commercially available triphos-ligated Ni-complex that enables highly efficient and selectivetransformation of aromatic, heterocyclic, and aliphatic nitriles including fatty nitriles to prepare functionalized primaryalcohols. Further, the synthetic applicability of this Ni-based protocol is presented for the selective conversion of nitrileto alcoholic group in structurally diverse and complex drug molecules as well as agrochemicals. The resulting products,alcohols are indispensable chemicals commonly used in organic synthesis and life sciences as well as material and energytechnologies.
Roman cement mortar prepared by a multi-stage mixing process
(Consejo Superior de Investigaciones Científicas, 2025) Daňková, Jana; Mec, Pavel; Gabor, Roman; Bujdoš, David; Majstríková, Tereza; Valentová, Adéla; Šafrata, Jiří
Roman cement is the predecessor to modern Portland cement. Nowadays, it is a very promising product with lower CO2 emissions, frequently used to restore historical objects. However, there are still many practical problems as a setting that can be affected in several ways. One possibility is the multistage mixing of fresh mortar, a practical historical method that has not yet been scientifically investigated. This article presents an experimental study investigating the effect of multistage mixing on the properties of fresh and hardened mortar. The properties and structure of the mortar were compared with a reference mortar (retardened by citric acid). Multistage mixing affects fresh mortars with optimal consistency and a workability time of 120 minutes. The influence of mixing on the hydration process and structural formation is characterized by isothermal calorimetry and SEM. Comparison of reference and modified mixing mortars exhibits differences in hydration process, structure, and initial strength, but no significant effect at 90 days strength.
Mass transport limitations in plasmonic photocatalysis
(American Chemical Society, 2024) Henrotte, Olivier; Kment, Štěpán; Naldoni, Alberto
The interpretation of mechanisms governing hot carrier reactivity on metallic nanostructures is critical, yet elusive, for advancing plasmonic photocatalysis. In this work, we explored the influence of the diffusion of molecules on the hot carrier extraction rate at the solid-liquid interface, which is of fundamental interest for increasing the efficiency of photodevices. Through a spatially defined scanning photoelectrochemical microscopy investigation, we identified a diffusion-controlled regime hindering the plasmon-driven photochemical activity of metallic nanostructures. Using low-power monochromatic illumination (<2 W cm(-2)), we unveiled the hidden influence of mass transport on the quantum efficiency of plasmonic photocatalysts. The availability of molecules at the solid-liquid interface directly limits the extraction of hot holes, according to their nature and energy, at the reactive spots in Au nanoislands on an ultrathin TiO2 substrate. An intriguing question arises: does the mass transport enhancement caused by thermal effects unlock the reactivity of nonthermal carriers under steady state?
A comparison of non-destructive defect detection methods for steel wire ropes
(MM Science, 2024) Lesňák, Michal; Kroupa, Jan; Barčová, Karla; Miškay, Marek; Jursa, Dominik
Steel wire ropes are among the essential technical elements widely used in many industries. The impeccable condition of these elements has a major impact on the safety of entire facilities where they are applied, be it construction, mining, agriculture, transport, engineering or another area. This article focuses on comparing two non-destructive methods designed to study the internal defects of steel wire ropes. They are defectoscopes with different principles of operation, namely the MID-3 magnetic defectoscope with both excitation and detection of the magnetic field by means of induction coils, and the REMA defectoscope with Hall sensors. Four reference samples of steel wire ropes used in underground mines with well-defined defects corresponding to damage due to fatigue of the wire rope material were created for the study. Based on the experiments performed, it was confirmed that defectoscopes working on the principle of Hall sensors can detect metal cross section loss adequately.
Microwave pyrolysis-prepared engineering carbons from corn cobs and red mombin seeds towards xylene adsorption
(Elsevier, 2024) Matějová, Lenka; Vaštyl, Michal; Jankovská, Zuzana; Cichoňová, Petra; Peikertová, Pavlína; Šeděnková, Ivana; Cruz, Gerardo Juan Francisco; Veliz, Jose Luis Solis; Kania, Ondřej
High-quality biochars/activated carbons were prepared, optimizing individual parameters of energetically-save microwave pyrolysis (raw material loading - 20 vs. 60 g, nitrogen atmosphere - flow vs. batch, ZnCl2 activation) from two agricultural wastes - corn cobs, red mombin seeds. Most promising carbons were examined for gaseous xylene adsorption and showed higher sorption capacity (similar to 250-475 mg(xylene) g(-1)) than commercial carbon (similar to 214 mg(xylene) g(-1)). ZnCl2 activation of both raw materials reduces the fixed carbon content and increases volatiles in activated carbon, suggesting microwave pyrolysis of activated feedstock should take 25 min. While biochars are microporous materials with inhomogeneous low-surface mesopore/macropore network, activated carbons are highly microporous-mesoporous. ZnCl2 activation of both raw materials contributes to formation of extensive high-surface mesopore network (with pore-size < 20 nm) and enlargement of micropore-size, but does not affect the micropore volume. ZnCl2 activation increases H-2 and decreases CH4 production. Microwave pyrolysis of larger raw material loading with ZnCl2 leads to CO2 increase. Best xylene adsorption capacity (475 mg(xylene) g(-1)) was determined for activated carbon produced from 60 g loading of corn cobs in batch nitrogen atmosphere, showing the largest micropore volume, lowest surface polarity and medium rate of graphitization. Large micropore volume, low surface polarity and high rate of graphitization of carbon are xylene sorption capacity-determining factors.
A general atomically dispersed copper catalyst for C–O, C–N, and C–C bond formation by carbene insertion reactions
(Elsevier, 2024) Wang, Qiang; Qi, Haifeng; Ren, Yujing; Cao, Zhusong; Junge, Kathrin; Jagadeesh, Rajenahally V.; Beller, Matthias
The implementation of heterogeneous catalysts in advanced organic synthesis provides basis for the sustainable and cost-effective preparation of pharmaceuticals, agrochemicals, and other structurally complex molecules. Crucial for such applications is the design of appropriate catalytic materials with high selectivity and functional group compatibility. Although many homogeneous catalysts are well known for this purpose, heterogeneous ones, specifically those based on non -noble metals, are scarce. Here, we present the preparation and wide-ranging applications of a specific atomically dispersed copper catalyst for highly selective carbene insertion reactions of diazo compounds with alcohols, phenols, amines, thiols, and N -heterocycles. The optimal catalyst (Cu-NC/Al 2 O 3 ) contains Al 2 O 3 -supported copper -based single atoms coordinated with nitrogen species, which can be conveniently prepared by the pyrolysis of Cu-MOF-303. The resulting catalyst allows for the selective formation of C-O, C-N, and C-C bonds in functionalized and structurally diverse molecules (e.g., complex natural products and drugs), including highly sensitive alkynes and azides.
Influence of the chemical composition of leachates on the results of ecotoxicity tests for different slag types
(Elsevier, 2024) Pavlovský, Jiří; Seidlerová, Jana; Pěgřimočová, Zuzana; Vontorová, Jiřina; Motyka, Oldřich; Michalska, Monika; Smutná, Kateřina; Roupcová, Petra; Novák, Vlastimil; Matějka, Vlastimil; Vlček, Jozef
In this study, four ecotoxicological tests on Vibrio fischeri bacteria, Sinapis alba L. (white mustard), Daphnia magna S. (daphnia's) and earthworms were performed for three types of aqueous slag (ladle, blast furnace and converter) leachates with two-grain sizes (<4 mm, <10 mm). Concentrations of toxic elements and concentrations of Cr(VI), Ca, Na, Al, and other ions were determined. The raw slags were analyzed using X-ray fluorescence spectroscopy (XRFS), and major substances were determined by X-ray powder diffraction (XRD). The aqueous slag leachates passed ecotoxicological tests and met the required criteria, showing no toxicity to Vibrio fischeri and complying with white mustard test criteria. According to the results of the ecotoxicity tests with daphnia, the blast furnace slag samples were not ecotoxic, while two other slag samples were found to be entirely compliant. Characterization of the slags showed that the effect of element/ion leachability and slag grain size is essential. Biplot principal component analysis (PCA) showed that grain size does not significantly affect the separation of individuals on the plane. A positive correlation on toxicity was found with pH, conductivity, calcium content, dissolved content, salinity and fluoride concentration, whereas a negative correlation was found with magnesium concentration, dissolved organic carbon and potassium concentration. The effective concentration at 50% inhibition (EC50) value for Vibrio fischeri correlated with the first dimension of bivariate assessment. In summary, it was found that the investigated slags can be effectively reused as they comply with regulations and do not endanger the environment.

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