Influence of Microstructure and Surface Activation of Dual‐Phase Membrane Ce0.8Gd0.2O2−δ–FeCo2O4 on Oxygen Permeation

Dual‐phase oxygen transport membranes are fast‐growing research interest for application in oxyfuel combustion process. One such potential candidate is CGO‐FCO (60 wt% Ce_0.8Gd_0.2O_2?δ–40 wt% FeCo₂O₄) identified to provide good oxygen permeation flux with substantial stability in harsh atmosphere. Dense CGO‐FCO membranes of 1 mm thickness were fabricated by sintering dry pellets pressed from powders synthesized by one‐pot method (modified Pechini process) at 1200°C for 10 h. Microstructure analysis indicates presence of a third orthorhombic perovskite phase in the sintered composite. It was also identified that the spinel phase tends to form an oxygen deficient phase at the grain boundary of spinel and CGO phases. Surface exchange limitation of the membranes was overcome by La_0.6Sr_0.4Co_0.2Fe_0.8O_3?δ (LSCF) porous layer coating over the composite. The oxygen permeation flux of the CGO‐FCO screen printed with a porous layer of 10 μm thick LSCF is 0.11 mL/cm² per minute at 850°C with argon as sweep and air as feed gas at the rates of 50 and 250 mL/min.     

Predicting the electrospinnability of polymer solutions with electromechanical simulation

The number of polymers successfully electrospun is increasing, and methods are needed predict the electrospinnability of polymers. With such methods, researchers should consider the polymer solution parameters and perform measurements in conditions that mimic the electrospinning process. A novel test method based on the electromechanical simulation of the fiber formation was developed. We formed fibers by mechanically dragging a conductive ball from the solution at an applied voltage and measuring the electrical current. The changes in the time of the electrical current (the ball current) reflect the fiber‐formation process, which depended on certain polymer solution properties (e.g., viscosity, surface tension, liquid flow) and on the influence of charges on the fiber surface. The data obtained with the proposed method was compared with experimental data from electrospinning trials with the spinneret and bubble electrospinning. The results demonstrate that the ball‐current method made it possible to predict the polymer solution behavior in the electrospinning process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41091.     

Modeling of enterprise management structure for data leakage evaluation

Modern organizations strongly rely on various forms of data, ranging from communication technologies to bookkeeping and manufacturing. It is a crucial asset of any enterprise, requiring special attention security-wise. One of the data security areas currently in focus is data leakage. It may occur due to malicious attacks, human error, unintentional data sharing, etc. Therefore it is important to predict all data leakage possibilities and prevent them. This paper proposes an Enterprise Management Structure (EMS) model for information flow data leakage probability estimation. The model evaluates the probability of data leakage according to possible human error and summarized security properties for data processing and transfer. Four different versions of small EMS are analyzed using the proposed model. The study concludes that its results meet expert evaluation tendencies and correlate with Bell-LaPadula confidentiality model.     

Camera for High-Speed THz Imaging

Journal of Infrared, Millimeter, and Terahertz Waves - We present a 24 × 24 pixel camera capable of high-speed THz imaging in power-detection mode. Each pixel of the sensor array consists of a...     

Antimicrobial dual-cured photopolymers of vanillin alcohol diglycidyl ether and glycerol dimethacrylate

Considering the current efforts for to develop new antimicrobial polymers from renewable resources suitable for application in environmentally friendly light-based technologies, novel dual-cured photopolymers of vanillin alcohol diglycidyl ether and glycerol dimethacrylate are developed. The kinetics of the sequential and simultaneous dual-curing processes, combining free radical and cationic photopolymerizations, is investigated by real-time photorheometry. Comparison of dual-curing systems with different ratios of biobased epoxy and acrylate monomers revealed that the increase in the acrylate content increases the photocuring rate and improves the mechanical performance (Young's modulus increases from 76.64 to 190.71 MPa) and thermal stability (the 10% weight loss increases from 227 to 274°C) of the polymers, while the increase in the vanillin epoxy content results in better antimicrobial activity. Developed photopolymers create unfavorable conditions for the growth of microorganisms and reduce their population by up to 0% in 24 h. The excellent antibacterial and antifungal activity of new photopolymers allows them to be considered as biobased alternatives to petroleum-based antimicrobial coatings, films, or optical 3D printed objects.     

Tailoring Structure,Composition, and Energy Storage Properties of MXenes from Selective Etching of In‐Plane,Chemically Ordered MAX Phases

The exploration of 2D solids is one of our time's generators of materials discoveries. A recent addition to the 2D world is MXenes that possses a rich chemistry due to the large parent family of MAX phases. Recently, a new type of atomic laminated phases (coined i‐MAX) is reported, in which two different transition metal atoms are ordered in the basal planes. Herein, these i‐MAX phases are used in a new route for tailoriong the MXene structure and composition. By employing different etching protocols to the parent i‐MAX phase (Mo_2/3Y_1/3)₂AlC, the resulting MXene can be either: i) (Mo_2/3Y_1/3)₂C with in‐plane elemental order through selective removal of Al atoms or ii) Mo_1.33C with ordered vacancies through selective removal of both Al and Y atoms. When (Mo_2/3Y_1/3)₂C (ideal stoichiometry) is used as an electrode in a supercapacitor—with KOH electrolyte—a volumetric capacitance exceeding 1500 F cm^?3 is obtained, which is 40% higher than that of its Mo_1.33C counterpart. With H₂SO₄, the trend is reversed, with the latter exhibiting the higher capacitance (≈1200 F cm^?3). This additional ability for structural tailoring will indubitably prove to be a powerful tool in property‐tailoring of 2D materials, as exemplified here for supercapacitors.     

2D Transition Metal Carbides (MXenes) for Carbon Capture

Global warming caused by burning of fossil fuels is indisputably one of mankind's greatest challenges in the 21st century. To reduce the ever‐increasing CO₂ emissions released into the atmosphere, dry solid adsorbents with large surface‐to‐volume ratio such as carbonaceous materials, zeolites, and metal–organic frameworks have emerged as promising material candidates for capturing CO₂. However, challenges remain because of limited CO₂/N₂ selectivity and long‐term stability. The effective adsorption of CO₂ gas (≈12 mol kg^?1) on individual sheets of 2D transition metal carbides (referred to as MXenes) is reported here. It is shown that exposure to N₂ gas results in no adsorption, consistent with first‐principles calculations. The adsorption efficiency combined with the CO₂/N₂ selectivity, together with a chemical and thermal stability, identifies the archetype Ti₃C₂ MXene as a new material for carbon capture (CC) applications.     

InGaN quantum dot formation mechanism on hexagonal GaN/InGaN/GaN pyramids

Growing InGaN quantum dots (QDs) at the apex of hexagonal GaN pyramids is an elegant approach to achieve a deterministic positioning of QDs. Despite similar synthesis procedures by metal organic chemical vapor deposition, the optical properties of the QDs reported in the literature vary drastically. The QDs tend to exhibit either narrow or broad emission lines in the micro-photoluminescence spectra. By coupled microstructural and optical investigations, the QDs giving rise to narrow emission lines were concluded to nucleate in association with a (0001) facet at the apex of the GaN pyramid.     

Thermal stability of Al1−xInxN (0 0 0 1) throughout the compositional range as investigated during in situ thermal annealing in a scanning transmission electron microscope

The thermal stability of Al_1?xIn_xN (0 ? x ? 1) layers was investigated by scanning transmission electron microscopy (STEM) imaging, electron diffraction, and monochromated valence electron energy loss spectroscopy during in situ annealing from 750 to 950 °C. The results show two distinct decomposition paths for the layers richest in In (Al_0.28In_0.72N and Al_0.41In_0.59N) that independently lead to transformation of the layers into an In-deficient, nanocrystalline and a porous structure. The In-richest layer (Al_0.28In_0.72N) decomposes at 750 °C, where the decomposition process is initiated by In forming at grain boundaries and is characterized by an activation energy of 0.62 eV. The loss of In from the Al_0.41In_0.59N layer was initiated at 800 °C through continuous desorption. No In clusters were observed during this decomposition process, which is characterized by an activation energy of 1.95 eV. Finally, layers richest in Al (Al_0.82In_0.18N and Al_0.71In_0.29N) were found to resist thermal annealing, although the initial stages of decomposition were observed for the Al_0.71In_0.29N layer.     

W‐Based Atomic Laminates and Their 2D Derivative W1.33C MXene with Vacancy Ordering

Structural design on the atomic level can provide novel chemistries of hybrid MAX phases and their MXenes. Herein, density functional theory is used to predict phase stability of quaternary i‐MAX phases with in‐plane chemical order and a general chemistry (W_2/3M²_1/3)₂AC, where M² = Sc, Y (W), and A = Al, Si, Ga, Ge, In, and Sn. Of over 18 compositions probed, only two—with a monoclinic C2/c structure—are predicted to be stable: (W_2/3Sc_1/3)₂AlC and (W_2/3Y_1/3)₂AlC and indeed found to exist. Selectively etching the Al and Sc/Y atoms from these 3D laminates results in W_1.33C‐based MXene sheets with ordered metal divacancies. Using electrochemical experiments, this MXene is shown to be a new, promising catalyst for the hydrogen evolution reaction. The addition of yet one more element, W, to the stable of M elements known to form MAX phases, and the synthesis of a pure W‐based MXene establishes that the etching of i‐MAX phases is a fruitful path for creating new MXene chemistries that has hitherto been not possible, a fact that perforce increases the potential of tuning MXene properties for myriad applications.