Nonoxidative methane activation,coupling, and conversion to ethane,ethylene, and hydrogen over Fe/HZSM‐5, Mo/HZSM‐5, and Fe–Mo/HZSM‐5 catalysts in packed bed reactor

A high abundance of methane and its relatively low price make it an attractive raw feedstock for the production of ethylene, which is in the consumer demand in recent years. Direct catalytic nonoxidative conversion is interesting, because it could be utilized on natural gas well sites. Monometallic and bimetallic Fe and Mo catalysts were prepared for the purpose of the coupling to ethane and ethene. Three supported materials were synthesized with the following loading of metal: 2.5‐wt% Fe, 5.0‐wt% Fe, and 2.5‐wt% Mo on HZSM‐5. Process' chemical reactions were also catalyzed with a constant 2.5‐wt% Mo/HZSM‐5, which had different amounts of Fe, namely, 0.5, 1.0, and 2.5 wt%. Fourier transform infrared (FTIR), N₂ adsorption/desorption, NH₃ temperature‐programmed desorption (TPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X‐ray diffraction (XRD) were applied for characterization. Coke, accumulated on spent solids, was determined by thermogravimetric analysis (TGA). Activity was evaluated in quartz‐packed bed reactor. All surfaces suffered from deactivation due to carbon formation. The addition of Fe to Mo increased CH₄ reacted. The highest selectivity for alkenes was achieved over 1.0‐wt% Fe to 2.5‐wt% Mo/HZSM‐5. At the peak of performance, the C‐based reactivity was 52% for olefins and 2% for alkanes. Stability was accomplished over 2.5‐wt% Fe/HZSM‐5, where the rate of C₂ synthesis was comparatively stable for 20 hours of the time on stream. The selective C‐basis yield for C₂H₄ and C₂H₆ was 36% and 23%, respectively. The lowest measured quantity of (carbonaceous) by‐products was deposited on 2.5‐wt% Fe/HZSM‐5 after 26 hours. Propylene was detected very limitedly.     

Differences in safety belt use by race

The purpose of the study was to identify daytime differences in safety belt use by race. Safety belt use was investigated in a direct observation survey of drivers and front-outboard passengers throughout Michigan. Data were weighted to calculate statewide safety belt use rates by race. Race was assessed visually by trained observers. The study showed that motor vehicle occupants identified as Black had significantly lower safety belt use than those occupants identified as White or Other.     

Modeling of UAV/RPAS data traffic in space,air, and ground networks

Remotely piloted air systems (RPASs) are increasingly used for data transmission in the space-air-ground integrated networks (SAGINs). That is why it is important to know the possibilities and ways of integrating existing space, air and terrestrial networks for effective interaction with RPASs. This paper studies the issues of ensuring the required quality of service during heavy traffic in SAGIN and the choice of the necessary data transmission modes for this. Models of communication channels were created, including line-of-sight transmission (Model 1), public terrestrial network (PTN) (Model 2), low-orbit satellite transmission (Model 3) and PTN plus satellite transmission (Model 4). The relationships between models' performance and traffic parameters, channel bandwidths, bit errors, lost packets and models' topology were investigated using NetCracker Professional 4.1 software. The dependencies of the average utilization on the transaction size and the time between transactions with different statistical distribution laws were analyzed. The effect of different bandwidths was investigated. The influence of the bit error rate and the probability of packet fail chance on the channel performance was studied. The traffic characteristics in all models were compared.     

Bauschinger Effect in Microalloyed Steels: Part I. Dependence on Dislocation-Particle Interaction

The Bauschinger effect (yield stress decreasing at the start of reverse deformation after forward prestrain) is an important factor in strength development for cold metal forming technology. In steels, the magnitude of the Bauschinger effect depends on composition, through the presence of microalloy precipitates, and prior processing, through the size and distribution of microalloy precipitates and presence of retained work hardening. In this article, the microstructures of two (Nb- and Nb-V-microalloyed) steel plates, in terms of (Ti,Nb,V,Cu)-rich particle distributions and dislocation densities, have been quantitatively related to the Bauschinger parameters for the same processing conditions. For the 12- to 50-nm effective particle size range, the Bauschinger stress parameter increases with the particle number density and dislocation density increase. The relative influence of these two microstructure parameters is discussed.     

Optomechanical Processing of Silver Colloids: New Generation of Nanoparticle–Polymer Composites with Bactericidal Effect

The properties of materials at the nanoscale open up new methodologies for engineering prospective materials usable in high-end applications. The preparation of composite materials with a high content of an active component on their surface is one of the current challenges of materials engineering. This concept significantly increases the efficiency of heterogeneous processes moderated by the active component, typically in biological applications, catalysis, or drug delivery. Here we introduce a general approach, based on laser-induced optomechanical processing of silver colloids, for the preparation of polymer surfaces highly enriched with silver nanoparticles (AgNPs). As a result, the AgNPs are firmly immobilized in a thin surface layer without the use of any other chemical mediators. We have shown that our approach is applicable to a broad spectrum of polymer foils, regardless of whether they absorb laser light or not. However, if the laser radiation is absorbed, it is possible to transform smooth surface morphology of the polymer into a roughened one with a higher specific surface area. Analyses of the release of silver from the polymer surface together with antibacterial tests suggested that these materials could be suitable candidates in the fight against nosocomial infections and could inhibit the formation of biofilms with a long-term effect.     

Possibility of graphene growth by close space sublimation

Carbon films on the Si/SiO₂ substrate are fabricated using modified method of close space sublimation at atmospheric pressure. The film properties have been characterized by micro-Raman and X-ray photoelectron spectroscopy and monochromatic ellipsometry methods. Ellipsometrical measurements demonstrated an increase of the silicon oxide film thickness in the course of manufacturing process. The XPS survey spectra of the as-prepared samples indicate that the main elements in the near-surface region are carbon, silicon, and oxygen. The narrow-scan spectra of C1s, Si2p, O1s regions indicate that silicon and oxygen are mainly in the SiO _x (x ≈ 2) oxide form, whereas the main component of C1s spectrum at 284.4 eV comes from the sp²-hybridized carbon phase. Micro-Raman spectra confirmed the formation of graphene films with the number of layers that depended on the distance between the graphite source and substrate.     

Buckling Patterns of Graphene–Boron Nitride Alloy on Ru(0001)

Buckling nanopatterns of monoatomic layer 2D materials on metal substrates attract significant attention due to their rich interface morphology affecting electronic applications. An experimental–theoretical study of a 2D boron–nitrogen–carbon (B _{x /2}N _{x /2}C_1−x ) alloy on a Ru(0001) surface is conducted and a profound relation between the composition x and the degree of buckling is discovered. Experimentally, real carbon–boron–nitrogen alloys on the Ru(0001) surface are demonstrated and various morphologies of pure and mixed compounds are shown. Density functional theory calculations are further carried out using the supercells of graphene, hexagonal boron nitride (h‐BN), and random BNC on Ru(0001), as well as Monte Carlo simulations for elucidating the kinetics of their growth. The results show that unlike pure compounds (h‐BN or C), the carbon–boron–nitrogen mix on Ru(0001) mostly exists in an uncorrugated form, thus greatly improving the interface contact. The likely cause of the diminished corrugation is a softening of bond angular interactions in the alloy relative to the pure phases.     

Novel nanostructured pHEMA-TiO2 hybrid materials with efficient light-induced charge separation

We report on a new approach to the fabrication of an electronic material: organic-inorganic pHEMA-oxo-TiO(2) hybrid with efficient light-induced separation of charges. Particular attention is paid to the material nanoscale morphology. The size-selected 5.0 nm titanium oxo-alkoxy nanoparticles are prepared in a sol-gel reactor with rapid (turbulent) fluid micromixing and the ligand exchange results in a stable nanoparticulate precursor in HEMA solution, in which polymerization can be induced thermally or by photons. The obtained hybrid materials demonstrate the highest quantum yield of photoinduced charge separation of 50% and can store photoinduced electrons at a number density above 10% Ti atoms.     

Confined Catalytic Janus Swimmers in a Crowded Channel: Geometry‐Driven Rectification Transients and Directional Locking

Self‐propelled Janus particles, acting as microscopic vehicles, have the potential to perform complex tasks on a microscopic scale, suitable, e.g., for environmental applications, on‐chip chemical information processing, or in vivo drug delivery. Development of these smart nanodevices requires a better understanding of how synthetic swimmers move in crowded and confined environments that mimic actual biosystems, e.g., network of blood vessels. Here, the dynamics of self‐propelled Janus particles interacting with catalytically passive silica beads in a narrow channel is studied both experimentally and through numerical simulations. Upon varying the area density of the silica beads and the width of the channel, active transport reveals a number of intriguing properties, which range from distinct bulk and boundary‐free diffusivity at low densities, to directional “locking” and channel “unclogging” at higher densities, whereby a Janus swimmer is capable of transporting large clusters of passive particles.