High flux mesoporous MCM-48 membranes: Effects of support and synthesis conditions on membrane permeance and quality

This communication reports experimental efforts to synthesize defect-free mesoporous MCM-48 membranes with improved gas flux. We demonstrate a facile and inexpensive method of synthesizing defect-free supported MCM-48 membranes with improved N₂ and CO₂ permeance (>2 × 10⁻⁷ mol/m² s Pa) employing asymmetric supports for the membrane synthesis which contain layers of macropores possessing different pore sizes. The membranes prepared on asymmetric -alumina supports displayed higher gas permeance than those fabricated on symmetric supports (N₂ permeance <10⁻⁷ mol/m² s Pa) as confirmed by unsteady-state gas permeation experiments. Further improvement in gas permeance was achieved by covering one face and the sides of the support with a ceramic tape during membrane synthesis.     

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.     

Hypoglycemia,Vascular Disease and Cognitive Dysfunction in Diabetes: Insights from Text Mining-Based Reconstruction and Bioinformatics Analysis of the Gene Networks

Hypoglycemia has been recognized as a risk factor for diabetic vascular complications and cognitive decline, but the molecular mechanisms of the effect of hypoglycemia on target organs are not fully understood. In this work, gene networks of hypoglycemia and cardiovascular disease, diabetic retinopathy, diabetic nephropathy, diabetic neuropathy, cognitive decline, and Alzheimer’s disease were reconstructed using ANDSystem, a text-mining-based tool. The gene network of hypoglycemia included 141 genes and 2467 interactions. Enrichment analysis of Gene Ontology (GO) biological processes showed that the regulation of insulin secretion, glucose homeostasis, apoptosis, nitric oxide biosynthesis, and cell signaling are significantly enriched for hypoglycemia. Among the network hubs, INS, IL6, LEP, TNF, IL1B, EGFR, and FOS had the highest betweenness centrality, while GPR142, MBOAT4, SLC5A4, IGFBP6, PPY, G6PC1, SLC2A2, GYS2, GCGR, and AQP7 demonstrated the highest cross-talk specificity. Hypoglycemia-related genes were overrepresented in the gene networks of diabetic complications and comorbidity; moreover, 14 genes were mutual for all studied disorders. Eleven GO biological processes (glucose homeostasis, nitric oxide biosynthesis, smooth muscle cell proliferation, ERK1 and ERK2 cascade, etc.) were overrepresented in all reconstructed networks. The obtained results expand our understanding of the molecular mechanisms underlying the deteriorating effects of hypoglycemia in diabetes-associated vascular disease and cognitive dysfunction.     

Regeneration of Pd/TiO2 catalyst deactivated in reductive CCl4 transformations by the treatment with supercritical CO2, ozone in supercritical CO2 or oxygen plasma

Carbonaceous deposits formation was established as the primary reason of Pd/TiO₂ catalyst deactivation during reductive processing of CCl₄ to form hydrodechlorination and oligomerization products. Three methods of carbonaceous deposits elimination were tested: (1) extraction by supercritical CO₂, (2) oxidation by ozone in supercritical CO₂, and (3) low-temperature glow-discharge oxygen plasma treatment. Synchronic thermal analysis confirms effective carbonaceous deposits removal during regeneration by ozone or low temperature glow-discharge oxygen plasma; by XPS deep oxidation of surface Pd after oxidative treatment (by ozone or oxygen plasma) was found. Thus H₂ reduction was proposed as the second step making possible full regeneration of initial catalytic activity of Pd/TiO₂.     

Formic Acid Production Via Methane Peroxide Oxidation Over Oxalic Acid Activated Fe-MFI Catalysts

Topics in Catalysis - The process of synthesis of formic acid via partial peroxide oxidation of methane over Fe-MFI zeolites, as well as the influence of the catalyst activation by oxalic acid on...     

Complex Formation of Divalent Cations with Carboxylic Acid Resins as a Factor Determining Different Stationary States of Their Swelling

Three samples of carboxylic acid gel-type cross-linked polyelectrolytes were examined by registering the extent and kinetics of their volume change depending on the temperature, concentration, and nature of external electrolyte solutions, as well as the initial state (ionic form, water content) of the bead. It is found that in some systems the swelling of the bead (as a result of lowering the temperature) proceeds much more slowly than the preceding shrinking (as a result of the increase of temperature). Moreover, the initial volume of the bead is not restored, and a new stationary state of swelling is established. By means of optical dilatometry, it is found that in the systems in which the differences in the stationary states of swelling are found, the beads display plasto-elastic properties, whereas in the absence of such differences the beads show elastic properties. It is found that different stationary states of swelling are also established when the beads of copolymer of methacrylic acid cross-linked with divinylbenzene in Na⁺ form in the dry state and in the NaCl solution-swollen state are placed into a solution of a divalent cation salt. The difference in the stationary states of swelling reaches 12% in 4 N NiCl₂ solution. The substantial differences in the swelling behavior and viscoelastic properties of the resins in their Na⁺, Mg²⁺, Ca²⁺, and Ni²⁺ forms are interpreted in terms of formation of different kinds of complexes of functional groups of the polymer with Ca²⁺ and Ni²⁺ ions.     

Deformation Control During Thermal Treatment of Electrospun PbZr0.52Ti0.48O3 Nanofiber Mats

This paper focuses on the deformation origin of PbZr_0.52Ti_0.48O₃ (PZT) fiber mats obtained by electrospinning. The main cause of deformation of the green mats during heating was found to be a nonuniform relaxation of the stretched PVP polymer, due to nonuniform thermal decomposition of the Pb‐hexanoate in the fibers. This relaxation starts under 100°C, well below the polymer decomposition temperature. The shrinkage was found to accelerate above the polymer glass transition point, giving rise to an overall linear change of almost 50%. The “green” PZT mats were easily separated from the collector by first depositing a pure PVP sublayer on the collector. An optimal fabrication and slow multistep thermal treatment process that provides fiber mats with desired PZT phase and overcomes the nonuniform deformation is described.     

Thermophysical and mechanical properties of novel high-entropy metal nitride-carbides

In this work, a novel (Hf_0.2Zr_0.2Ta_0.2Nb_0.2Ti_0.2)(N_0.5C_0.5) high-entropy nitride-carbide (HENC-1) with multi-cationic and -anionic sublattice structure was reported and their thermophysical and mechanical properties were studied for the first time. The results of the first-principles calculations showed that HENC-1 had the highest mixing entropy of 1.151R, which resulted in the lowest Gibbs free energy above 600 K among HENC-1, (Hf_0.2Zr_0.2Ta_0.2Nb_0.2Ti_0.2)N high-entropy nitrides (HEN-1), and (Hf_0.2Zr_0.2Ta_0.2Nb_0.2Ti_0.2)C high-entropy carbides (HEC-1). In this case, HENC-1 samples were successfully fabricated by hot-pressing sintering technique at the lowest temperature (1773 K) among HENC-1, HEN-1 and HEC-1 samples. The as-fabricated HENC-1 samples showed a single rock-salt structure of metal nitride-carbides and high compositional uniformity. Meanwhile, they exhibited high microhardness of 19.5 ± 0.3 GPa at an applied load of 9.8 N and nanohardness of 33.4 ± 0.5 GPa and simultaneously possessed a high bulk modulus of 258 GPa, Young's modulus of 429 GPa, shear modulus of 176 GPa, and elastic modulus of 572 ± 7 GPa. Their hardness and modulus are the highest among HENC-1, HEN-1 and HEC-1 samples, which could be attributed to the presence of mass disorder and lattice distortion from the multi-anionic sublattice structure and small grain in HENC-1 samples. In addition, the thermal conductivity of HENC-1 samples was significantly lower than the average value from the “rule of mixture” between HEC-1 and HEN-1 samples in the range of 300-800 K, which was due to the presence of lattice distortion from the multi-anionic sublattice structure in HENC-1 samples.     

Self-disproportionation of Enantiomers (SDE) of Chiral Nonracemic Amides via Achiral Chromatography

This article is based on a review of literature devoted to the phenomenon of SDE via achiral chromatography since the appearance of the seminal work of Professor Emanuel Gil-Av. The discussed examples of chromatographic studies are related to amides derived from chiral amines and α- and β-amino acids. We discuss the observed SDE magnitude as a function of a compound's structure, and composition of eluent and stationary phases, providing some mechanistic considerations. Particular emphasis is given to the aspect of SDE via achiral chromatography as an emerging unconventional enantiomeric purification technique.