Search

Hydrogen is considered the cleanest, most environmentally friendly fuel and energy carrier required for the gradual decarbonisation of many industrial sectors. Using ammonia as a Cox-free source of hydrogen is the most reasonable and most applicable method. This paper studies the properties and activity of cobalt catalysts in the ammonia decomposition reaction using a plasma-catalytic system. The effect of catalyst type (supported versus bulk) was evaluated. The catalysts were examined using XRD, STEM-EDX, and sorption techniques (N2 physisorption, TGA-TPR, H2-TPD, CO2-TPD) to reveal the influence of physicochemical properties of these two types of catalysts on the efficiency of NH3 decomposition in the plasma-catalytic process using a gliding discharge plasma. The results disclose that the supported-type catalyst (Ba-Co/CeO2) decomposed NH3 more effectively than the bulk-type catalyst (Co/Ce/Ba). At discharge power of 300 W and flow rate of 180 dm3 h–1 of NH3:N2 mixture (50/50 vol%), the ammonia conversion over the Ba-Co/CeO2 catalyst was 70%, whereas over the Co/Ce/Ba catalyst it was only 21%. The favourable performance of the supported-type catalyst was attributed to a more thermally stable surface area compared with the bulk-type catalyst. Smaller and more stable cobalt nanoparticles (NPs) with numerous weak hydrogen adsorption sites were also seen. Meanwhile, the strong basic sites were generated, improving the electron-donating ability of the surface active sites. High ammonia conversion and relatively low-energy consumption of the plasma-catalytic ammonia decomposition over Ba-Co/CeO2 make it suitable for practical hydrogen production applications, such as fuel cells and hydrogen storage.

Ni-rich layered oxides are the most promising cathode materials for high-energy-density Li-ion batteries. Full utilization of their potential resulting from high nickel content, mainly high capacity, is impaired due to the rapid performance degradation. Mitigating the main limitations of Ni-rich materials is possible through element doping. In this work, a series of LiNi0.6Mn0.2Co0.2O2 (NMC622) cathode materials doped with sodium and/or neodymium was synthesized and systematically studied (XRD, SEM, TEM, STEM-EDX, XPS, galvanostatic charge/discharge tests, cyclic voltammetry). The strategies of single-element and dual-element doping were applied to study the effect of Na and Nd doping on the electrochemical performance of the modified NMC622 materials. The Na-doped NMC622 material exhibited improved capacity retention of 80.5% after 100 cycles, which is superior to the undoped one (62.7%), possibly owing to enlarged Li layer spacing and decreased Li ion migration activation energy. For the Nd-doped NMC622 cathode material, both the initial discharge capacity and capacity retention were much improved compared to the undoped NMC622. This can be related to the enhanced structural stability brought by the formation of strong bonds between neodymium and oxygen atoms. In contrast, the dual-doping of Na and Nd in NMC622 material resulted in much poorer electrochemical and cycling performance, but the reason for this is unclear. The experimental data suggest that the combination of Na and Nd dopants caused the deterioration of crystal structure, possibly due to the introduced impurities. This consequently affected the structural stability of the dual-doped material, leading to the lowest discharge capacity and capacity retention among the studied NMC622 materials.

In this research, we developed boron-rich nanoparticles that can be used for boron neutron capture therapy as potential carriers for boron delivery to cancerous tissues. Functionalized carbonated boron nitride nanostructures (CBNs) were successfully synthesized in self-propagating combustion waves in mixtures of high-nitrogen explosives and boron compounds. The products’ composition, morphology, and structural features were investigated using Fourier transform infrared spectroscopy, powder X-ray diffraction, low-temperature nitrogen sorption analysis, thermogravimetric analysis, high-resolution scanning electron microscopy, and high-resolution transmission electron microscopy. The extreme conditions prevailing in combustion waves favor the formation of nanosized CBN hollow grains with highly disordered structures that are properly functionalized on the surface and inside the particles. Therefore, they are characterized by high porosity and good dispersibility in water, which are necessary for medical applications. During biological tests, a concentration-dependent effect of the obtained boron nitride preparations on the viability of normal and neoplastic cells was demonstrated. Moreover, the assessment of the degree of binding of fluorescently labeled nanoparticles to selected cells confirmed the relationships between the cell types and the concentration of the preparation at different incubation time points.

Extracellular vesicles (EVs) released from primary cell lines, originating from resected tissues during biopsies in patients with non-small cell lung cancer (NSCLC) revealing adenocarcinoma and squamous cell carcinoma subtypes, were examined for membrane proteomic fingerprints using a proximity barcoding assay. All the collected EVs expressed canonical tetraspanins (CD9, CD63, and CD81) highly coexpressed with molecules such as lysosome-associated membrane protein-1 (LAMP1–CD107a), sialomucin core protein 24 (CD164), Raph blood group (CD151), and integrins (ITGB1 and ITGA2). This representation of the protein molecules on the EV surface may provide valuable information on NSCLC subtypes and offer new diagnostic opportunities as next-generation biomarkers in personalized oncology.

Abstract The electrochemical properties of metal oxides are very attractive and fascinating in general, making them a potential candidate for supercapacitor application. Vanadium oxide is of particular interest because it possesses a variety of valence states and is also cost effective with low toxicity and a wide voltage window. In the present study, vanadium oxide nanorods were synthesized using a modified sol–gel technique at low temperature. Surface morphology and crystallinity studies were carried out by using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy analysis. To the best of our knowledge, the as-prepared nanorods were tested with magnesium ion based polymer gel electrolyte for the first time. The prepared supercapacitor cell exhibits high capacitance values of the order of ~ 141.8 F g−1 with power density of ~ 2.3 kW kg−1 and energy density of ~ 19.1 Wh kg−1. The cells show excellent rate capability and good cycling stability.

The growing demand for efficient lithium-ion batteries to power vehicles and energy storage entails improving cathode material properties. Maintaining the stability of Ni-rich layered structure oxide cathodes is critical for long-term Li-ion battery operation. In this work, a series of LiNi0.6Mn0.2Co0.2O2 (NMC622) cathode materials doped with selected rare earth metal ions (La, Nd, Eu) of various concentrations (0.5-1.5 mol%) was synthesized and systematically studied (XRD, XPS, TEM, STEM-EDX, galvanostatic charge/discharge tests, cyclic voltammetry). The main goal of the research was to suppress the mixing of Ni/Li cations, which influences the electrochemical performance of LiNi0.6Mn0.2Co0.2O2 cathode materials by introducing rare earth elements using co-precipitation. The results showed that the La, Nd, Eu-doped materials exhibit significantly improved electrochemical properties, such as capacity, rate performance, capacity retention and Li+diffusivity compared to the pristine material. A clear dependence of the doped Ni-rich cathode material capacity on the degree of Ni/Li cation mixing was determined. The presence of a dopant (La, Nd or Eu) with a large radius, the tendency to form strong bonds with oxygen, and electrochemically inactive reduces Ni/Li disordering. It stabilizes the cathode structure, ensuring its better performance. The optimal content of La, Nd and Eu is 1.0, 0.5, and 0.5 mol%, respectively.

Recently, catalysts with hydrotalcites and hydrotalcite-derived compounds have attracted particular interest due to their specific properties, mostly well-developed texture, high thermal stability, and favorable acid–base properties. In this work, we report the investigation of ammonia synthesis on barium-promoted cobalt catalysts supported on hydrotalcite-derived Mg-Al mixed oxides with different Mg/Al molar ratios. The obtained catalysts were characterized using TGA-MS, nitrogen physisorption, XRPD, TEM, STEM-EDX, H2-TPD, CO2-TPD, and tested in ammonia synthesis (470 °C, 6.3 MPa, H2/N2 = 3). The studies revealed that the prepared Mg-Al mixed oxides are good candidates as support materials for Co-based catalysts. However, interestingly, the support composition does not influence the activity of Ba/Co/Mg-Al catalysts. The change in Mg/Al molar ratio in the range of 2–5 did not significantly change the catalyst properties. All the catalysts are characterized by similar textural, structural, and chemisorption properties. The similar density of basic sites on the surface of the studied catalysts was reflected in their comparable performance in ammonia synthesis.

Hydrogen can be incorporated within a solid and drastically modify its electronic and structural state. Here, the authors report reversible binding of H+ ions to chalcogens in the Bi2Te3 class of topological insulators and magnets, allowing Fermi level tuning into the bulk gap without altering carrier mobility or the bandstructure.

Ammonia is currently considered a promising compound for the chemical storage of hydrogen and as an energy carrier. However, large-scale ammonia production is not possible without an active and stable catalyst enabling efficient, long-term work without the need for its replacement. In this paper, the extended stability studies of the highly active promoted cobalt catalyst for ammonia synthesis were carried out. The long-term activity measurements in NH3 synthesis reaction under conditions close to the industrial ones (400–470 °C, 6.3 MPa, H2/N2 = 3) were compiled with the characterization of catalyst properties on different stages of its work using N2 physisorption, XRPD, STEM-EDX, and H2-TPD. The accelerated aging method was used to simulate the deterioration of catalyst performance during industrial operation. Textural and structural characteristics revealed that the tested catalyst is highly resistant to high temperatures. The lack of significant changes in the specific surface area, morphology of the catalyst particles, surface distribution of elements, and chemisorption properties of cobalt surface during long-term heating (436 h) at 600 °C suggests that stable operation of the catalyst is possible in an ammonia synthesis reactor in the temperature range of 400–470 °C without the risk of losing its beneficial catalytic properties over time. The decline in catalyst activity during the long-term stability test was less than 10%.

This paper presents the status of developments worldwide regarding use of hybrid rocket motors for space transportation. Historical roots are presented and reasons for revisiting hybrid technology after a few decades of limited interest are examined. Modern developments in sounding rockets, reusable suborbital systems and launch vehicles are discussed with particular focus on propellant technology. Various propellant combinations include use of liquid oxygen, hydrogen peroxide, nitrous oxide and nitrous oxide-oxygen mixtures as oxidizers. Different fuels are considered, taking into account performance, as well as inter alia obtainable regression rates. Results of preliminary calculations for vehicles using different propellant combinations are presented and analysed. This is compared with proposed configurations of hybrid rockets worldwide. Unresolved problems and several unknowns are pointed out, including hybrid rocket motor scalability issues, large motor combustion instabilities, combustion efficiency of metalized fuels, propellant volumetric performance and mass of fuel residuals in case of wagon wheel grain geometry. It is discussed whether new-space hybrid launch vehicles, while typically with limited stage reusability, may be cost-competitive in regard to other chemical rocket propulsion system developments. The paper is summarized with a list of potential future advances and technical opportunities. The main purpose of the conducted research is to provide a comparison between different hybrid propulsion technologies available, or currently under development, worldwide.

In this paper, thermal oxidation resistance of silicide-coated niobium substrates was tested in a temperature range of 1300–1450°C using an HVOF burner. Pure niobium specimens were coated using the pack cementation CVD method. Three different silicide thickness coatings were deposited. Thermal oxidation resistance of the coated niobium substrates was tested in a temperature range of 1300–1450°C using an HVOF burner. All samples that passed the test showed their ability to stabilize the temperature over a time of 30 s during the thermal test. The rise time of substrate temperature takes about 10 s, following which it keeps constant values. In order to assess the quality of the Nb-Si coatings before and after the thermal test, light microscopy, scanning electron microscopy (SEM) along with chemical analysis (EDS), X-ray diffraction XRD and Vickers hardness test investigation were performed. Results confirmed the presence of substrate Nb compounds as well as Si addition. The oxygen compounds are a result of high temperature intense oxidizing environment that causes the generation of SiO phase in the form of quartz and cristobalite during thermal testing. Except for one specimen, all substrate surfaces pass the high temperature oxidation test with no damages.

In this paper, we present a comparative analysis of the optical properties of non-polar and polar GaN/AlGaN multi-quantum well (MQW) structures by time-resolved photoluminescence (TRPL) and pressure-dependent studies. The lack of internal electric fields across the non-polar structures results in an improved electron and hole wavefunction overlap with respect to the polar structures. Therefore, the radiative recombination presents shorter decay times, independent of the well width. On the contrary, the presence of electric fields in the polar structures reduces the emission energy and the wavefunction overlap, which leads to a strong decrease in the recombination rate when increasing the well width. Taking into account the different energy dependences of radiative recombination in non-polar and polar structures of the same geometry, and assuming that non-radiative processes are energy independent, we attempted to explain the ‘S-shape’ behavior of the PL energy observed in polar GaN/AlGaN QWs, and its absence in non-polar structures. This approach has been applied previously to InGaN/GaN structures, showing that the interplay of radiative and non-radiative recombination processes can justify the ‘S-shape’ in polar InGaN/GaN MQWs. Our results show that the differences in the energy dependences of radiative and non-radiative recombination processes cannot explain the ‘S-shape’ behavior by itself, and localization effects due to the QW width fluctuation are also important. Additionally, the influence of the electric field on the pressure behavior of the investigated structures was studied, revealing different pressure dependences of the PL energy in non-polar and polar MQWs. Non-polar MQWs generally follow the pressure dependence of the GaN bandgap. In contrast, the pressure coefficients of the PL energy in polar QWs are highly reduced with respect to those of the bulk GaN, which is due to the hydrostatic-pressure-induced increase in the piezoelectric field in quantum structures and the nonlinear behavior of the piezoelectric constant.

This paper presents the development of indigenous hybrid rocket technology, using 98% hydrogen peroxide as an oxidizer. Consecutive steps are presented, which started with interest in hydrogen peroxide and the development of technology to obtain High Test Peroxide, finally allowing concentrations of up to 99.99% to be obtained in-house. Hydrogen peroxide of 98% concentration (mass-wise) was selected as the workhorse for further space propulsion and space transportation developments. Over the course nearly 10 years of the technology’s evolution, the Lukasiewicz Research Network—Institute of Aviation completed hundreds of subscale hybrid rocket motor and component tests. In 2017, the Institute presented the first vehicle in the world to have demonstrated in-flight utilization for 98% hydrogen peroxide. This was achieved by the ILR-33 AMBER suborbital rocket, which utilizes a hybrid rocket propulsion as the main stage. Since then, three successful consecutive flights of the vehicle have been performed, and flights to the Von Karman Line are planned. The hybrid rocket technology developments are described. Advances in hybrid fuel technology are shown, including the testing of fuel grains. Theoretical studies and sizing of hybrid propulsion systems for spacecraft, sounding rockets and small launch vehicles have been performed, and planned further developments are discussed.

Great Mosque of Damascus was built between 705 and 715 by the Umayyad Caliph al-Walid I. However, the origins of this building dates to the distant past. At first it was a location of an ancient Aramaean temple dedicated to the god Hadad. With Hellenization the temple was dedicated to Zeus and in the first century BC the Romans transformation it into the Temple of Jupiter Damascenus. In 391 Emperor Theodosius converted the temple into Christian Cathedral of Saint John. Erection of the mosque by Caliph al-Walid I was under strong influence of earlier constructions. Meaning and consequences of such transitions, from the Roman temple (there is almost no data of the Aramaic building) through the Christian Cathedral to the Islamic mosque is an interesting process. Issue not only within the art and architecture, but what is more, in a religious aspect of the continuity of sacred space.

Spontaneous and piezoelectric polarization in the nitrides is analyzed. The slab model was designed and proved to be appropriate to obtain the spontaneous polarization in AlN, GaN and InN. The spontaneous polarization and polarization related electric fields in AlN, GaN and InN were determined using DFT slab calculations. The procedure generates single value of spontaneous polarization in the nitrides. It was shown that Berry phase polarization may be applied to determination of spontaneous polarization by appropriate addition of polarization induced electric fields. The electric fields obtained from slab model are consistent with the Berry phase results of Bernardini et al. The obtained spontaneous polarization values are: 8.69*10-3 C/m2, 1.88*10-3 C/m2, and 1.96*10-3 C/m2 for AlN, GaN and InN respectively. The related Berry phase polarization values are 8.69*10-2 C/m2, 1.92*10-2 C/m2, and 2.86*10-2 C/m2, for these three compounds, respectively. The GaN/AlN multiquantum wells (MQWs) were simulated using ab intio calculations. The obtained electric fields are in good agreement with those derived from bulk polarization values. GaN/AlN MQWs structures, obtained by MBE growth were characterized by TEM and X-ray measurements. Time dependent photoluminescence measurements were used to determine optical transition energies in these structures. The PL obtained energies are in good agreement with ab initio data confirming overall agreement between theoretical and experimental data.

This article presents the method of size control of cobalt-doped zinc oxide nanoparticles (Zn1−xCoxO NPs) obtained by means of the microwave solvothermal synthesis. Zinc acetate dihydrate and cobalt(II) acetate tetrahydrate dissolved in ethylene glycol were used as the precursor. It has been proved by the example of Zn0.9Co0.1O NPs (x = 10 mol %) that by controlling the water quantity in the precursor it is possible to precisely control the size of the obtained Zn1−xCoxO NPs. The following properties of the obtained Zn0.9Co0.1O NPs were tested: skeleton density (helium pycnometry), specific surface area (BET), dopant content (ICP-OES), morphology (SEM), phase purity (XRD), lattice parameter (Rietveld method), average crystallite size (FW1/5/4/5M method and Scherrer’s formula), crystallite size distribution (FW1/5/4/5M method), and average particle size (from TEM and SSA). An increase in the water content in the precursor between 1.5% and 5% resulted in the increase in Zn0.9Co0.1O NPs size between 28 nm and 53 nm. The X-ray diffraction revealed the presence of only one hexagonal phase of ZnO in all samples. Scanning electron microscope images indicated an impact of the increase in water content in the precursor on the change of size and shape of the obtained Zn0.9Co0.1O NPs. The developed method of NPs size control in the microwave solvothermal synthesis was used for the first time for controlling the size of Zn1−xCoxO NPs.