hTERT-Driven Immortalization of RDEB Fibroblast and Keratinocyte Cell Lines Followed by Cre-Mediated Transgene Elimination

The recessive form of dystrophic epidermolysis bullosa (RDEB) is a crippling disease caused by impairments in the junctions of the dermis and the basement membrane of the epidermis. Using ectopic expression of hTERT/hTERT + BMI-1 in primary cells, we developed expansible cultures of RDEB fibroblasts and keratinocytes. We showed that they display the properties of their founders, including morphology, contraction ability and expression of the respective specific markers including reduced secretion of type VII collagen (C7). The immortalized keratinocytes retained normal stratification in 3D skin equivalents. The comparison of secreted protein patterns from immortalized RDEB and healthy keratinocytes revealed the differences in the contents of the extracellular matrix that were earlier observed specifically for RDEB. We demonstrated the possibility to reverse the genotype of immortalized cells to the state closer to the progenitors by the Cre-dependent hTERT switch off. Increased β-galactosidase activity and reduced proliferation of fibroblasts were shown after splitting out of transgenes. We anticipate our cell lines to be tractable models for studying RDEB from the level of single-cell changes to the evaluation of 3D skin equivalents. Our approach permits the creation of standardized and expandable models of RDEB that can be compared with the models based on primary cell cultures.     

Lewis number effect on the propagation of premixed flames in narrow adiabatic channels: Symmetric and non-symmetric flames and their linear stability analysis

The propagation of premixed flames with different Lewis numbers in a planar channel subject to a Poiseuille flow is considered within the diffusive-thermal model for steady and time-dependent cases. It was found that, depending on the Lewis number and the flow rate, symmetric and non-symmetric flames are possible. The existence of multiple steady solutions in cases of the low Lewis number is demonstrated. The time-dependent simulations carried out for high Lewis number flames also showed the symmetric and non-symmetric oscillatory solutions.Linear stability analysis of two-dimensional steady-states was performed using a practical method developed in the paper and applied to calculate the main eigenvalue. It was shown that for symmetric flames with a low Lewis number the increase in the flow rate leads to a loss of stability with subsequent formation of non-symmetric solutions. For flames with a high Lewis number the Poiseuille flow produces a stabilization effect. The results of the stability analysis were successfully compared with the results of direct numerical simulations.     

CAD of efficient TMmn0 single-mode elliptical applicators with coaxial excitation.

This paper suggests computational and engineering approaches to designing single-mode elliptical applicators for thermal processing of cylindrical samples of relatively small diameters. Through a systematic computational experimentation employing a 3D conformal FDTD model, we show that stable and efficient excitation of even and odd TMo modes of elliptical waveguides can be achieved by appropriate placing of two (one active and one passive) coaxial probes extended in the longitudinal direction of the cavity of relatively small height and by choosing the dimensions of the cavity. Effects produced by cylindrical loads inserted in the electric field maxima of the applicators featuring even TM010, TM110, and TM210 modes are studied for materials with different dielectric constants and the loss factors. It is shown that with the proposed excitation supported by simulation of energy coupling and dissipated power the elliptical structure is capable of operating any of these modes in a single-mode regime and generating satisfactory uniformity of the dissipated power within the cylindrical samples.     

Simulations of delamination in CFRP laminates: Effect of microstructural randomness

Due to their high specific strength and stiffness, fibre-reinforced composite materials are being increasingly used in structural applications where a high level of performance is important (e.g. aerospace, automotive, offshore structures, etc.). Performance in service of these composites is affected by multi-mechanism damage evolution under loading and environmental conditions. For instance, carbon fibre-reinforced laminates demonstrate a wide spectrum of failure mechanisms such as matrix cracking and delamination. These damage mechanisms can result in significant deterioration of the residual stiffness and load-bearing capacity of composite components and should be thoroughly investigated. The delamination failure mechanism is studied in this paper for a double cantilever beam (DCB) loaded in mode I. Several sensitivity studies are performed to analyse the effects of mesh density and of parameters of the cohesive law on the character of damage propagation in laminates. The microstructural randomness of laminates that is responsible for non-uniform distributions of stresses in them even under uniform loading conditions is accounted for in the model. The random properties are introduced with the use of Weibull’s two-parameter probability density function. Several statistical realisations are carried out which show that the effect of microstructure could significantly affect the macroscopic response emphasizing the need to account for microstructural randomness for accurate predictions of load-carrying capacity of laminate composite structures.     

The effect of Nb or Ta substitution into the M1 phase of the MoV(Nb,Ta)TeO selective oxidation catalyst

We use aberration corrected high-angle annular dark field (HAADF) imaging to systematically study, atomic column by atomic column, the effects of substituting Nb or Ta into the M1 phase of the MoV(Nb,Ta)TeO propane (amm)oxidation catalyst. The HAADF results indicate that the x,y coordinates of the metal sites within the M1 framework are unaffected by the substitution of either Nb or Ta for Mo. The HAADF analysis of the Ta-substituted catalyst demonstrated that the Ta preferentially substitutes into the pentagonal bipyramidal site, and by analogy, we anticipate that Nb substitutes similarly. Compositional analysis of the entire framework suggests that Ta/Nb behaves as a director of V among the octahedra that link the pentagonal rings, and the variable V occupancy may be correlated with variations in catalytic activities and selectivities. Finally, HAADF imaging provided evidence of coexistence of Ta-rich and Ta-poor domains. Similar phase segregation behavior may be present in Nb-substituted specimens, but would be very difficult to detect.     

The impact of thermal conductivity and diffusion rates on water vapor transport through gas diffusion layers

Proper water management in a hydrogen-fueled polymer electrolyte membrane (PEM) fuel cell is critical for performance and durability. A mathematical model has been developed to elucidate the effect of thermal conductivity and water vapor diffusion coefficient in the gas diffusion layers (GDLs). The fraction of product water removed in the vapor phase through the GDL as a function of GDL properties/set of material and component parameters and operating conditions has been calculated. The current model enables identification of conditions wherein condensation occurs in each GDL component. The model predicts the temperature gradient across various components of a PEM fuel cell, providing insight into the overall mechanism of water transport in a given cell design. The water condensation conditions and transport mode in the GDL components depend on the combination of water vapor diffusion coefficients and thermal conductivities of the GDL components. Different types of GDLs and water transport scenarios are defined in this work, based on water condensation in the GDL and fraction of water that the GDL removes through the vapor phase, respectively.     

Mesostructured mixed Mo–V–Nb oxides for propane ammoxidation

Mesostructured Mo–V–Nb mixed oxide phases were prepared by reacting inorganic precursors in the presence of cationic, anionic and alkylamine surfactants. The occurrence of these mesostructured phases was explained in part by charge-matching considerations at the inorganic–organic interface. Other interactions, such as covalent bonding between the surfactant headgroup and metal atoms, could direct the self-assembly process. Despite of the limited thermal stability of the mesophases, the air-calcined phases were catalytically active and selective for propane ammoxidation to acrylonitrile and acetonitrile. The selectivities to acrylonitrile and acetonitrile were as high as 26 and 49 mol%, respectively, at 66% propane conversion.     

Dual-templating of macroporous multicomponent MoVTeNbO x catalysts for propane ammoxidation to acrylonitrile

Thermally stable ordered porous MoVTeNbO _x phases displaying both macroporous and mesoporous structures were prepared for the first time by a dual-templating approach employing colloidal arrays of polystyrene spheres and non-ionic surfactants. The MoVTeNbO _x phases possessing such dual porosity were obtained after polystyrene spheres and non-ionic surfactants were removed in a low temperature calcination step. These hierarchical MoVTeNbO _x phases displaying bimodal pore structure transformed into macroporous rutile phase possessing nanocrystalline inorganic walls at high temperature. These MoVTeNbO _x rutile phases possessed high surface areas (70 m²/g), desirable pore architectures, robust nanocrystalline inorganic walls, and enhanced thermal stability (up to 600 °C). Although these macroporous MoVTeNbO _x rutile catalysts displayed lower activity in propane ammoxidation and lower acrylonitrile selectivity in propane ammoxidation as compared to the active and selective M1 phase, the novel synthesis method reported in these studies represents a promising general approach to design novel complex mixed metal oxides for a wide range of applications in selective oxidation catalysis.     

Sodalites as ultramicroporous frameworks for hydrogen separation at elevated temperatures: thermal stability, template removal, and hydrogen accessibility

Sodalite (SOD) is a highly promising porous structure for hydrogen separation from larger gas molecules due to the presence of small (～2.8 Å) six-membered ring openings of the sodalite cages. Thermal stability, template removal, and the release of encapsulated hydrogen were studied for low-silica (Si/Al = 1), high-silica (Si/Al = 5) and pure-silica (Si/Al = ∞) sodalites. The release of encapsulated hydrogen from sodalite cages was observed at 380, 550, and 480 °C for low-silica, high-silica and pure-silica sodalites, respectively, suggesting the operating temperatures for hydrogen separation employing these sodalite structures.