The effect of La2O3 and CeO2 modifiers on properties of Ni–Al catalysts for LNG prereforming

Ni/La–Al₂O₃ and Ni/Ce–Al₂O₃ catalysts with a small amount of promoters intended for prereforming of LNG were characterized by XRF, N₂ adsorption-desorption, XRD, H₂ chemisorption, HRTEM and XPS. The catalytic activity was evaluated in methane steam reforming both in the kinetic and diffusion regime, at temperatures characteristic of pre-reforming. Carbonaceous deposit was analysed by TPO-MS method. The nature and location of the coke were studied by HRTEM.La or Ce addition into Ni–Al system causes the increase of the active surface area of Ni by enhancing its dispersion. Studies at kinetic regime have shown that the promoted catalysts have almost twice the activity than reference Ni–Al catalyst. This effect was not confirmed by measurements in the diffusion regime on whole catalyst tablets. Almost identical textural properties of catalysts and diffusive limitations related to them but not the catalytic properties of the material itself appeared to be crucial factors. The presence of La (but not Ce) causes a significant increase in resistance to coking.     

Automatic discovery of interpretable planning strategies

Machine Learning - When making decisions, people often overlook critical information or are overly swayed by irrelevant information. A common approach to mitigate these biases is to provide...     

Advanced Spectroscopy and APBS Modeling for Determination of the Role of His190 and Trp103 in Mouse Thymidylate Synthase Interaction with Selected dUMP Analogues

A homo-dimeric enzyme, thymidylate synthase (TS), has been a long-standing molecular target in chemotherapy. To further elucidate properties and interactions with ligands of wild-type mouse thymidylate synthase (mTS) and its two single mutants, H190A and W103G, spectroscopic and theoretical investigations have been employed. In these mutants, histidine at position 190 and tryptophan at position 103 are substituted with alanine and glycine, respectively. Several emission-based spectroscopy methods used in the paper demonstrate an especially important role for Trp 103 in TS ligands binding. In addition, the Advanced Poisson–Boltzmann Solver (APBS) results show considerable differences in the distribution of electrostatic potential around Trp 103, as compared to distributions observed for all remaining Trp residues in the mTS family of structures. Together, spectroscopic and APBS results reveal a possible interplay between Trp 103 and His190, which contributes to a reduction in enzymatic activity in the case of H190A mutation. Comparison of electrostatic potential for mTS complexes, and their mutants, with the substrate, dUMP, and inhibitors, FdUMP and N4-OH-dCMP, suggests its weaker influence on the enzyme–ligand interactions in N4OH-dCMP-mTS compared to dUMP-mTS and FdUMP-mTS complexes. This difference may be crucial for the explanation of the ”abortive reaction” inhibitory mechanism of N4OH-dCMP towards TS. In addition, based on structural analyses and the H190A mutant capacity to form a denaturation-resistant complex with N4-OH-dCMP in the mTHF-dependent reaction, His190 is apparently responsible for a strong preference of the enzyme active center for the anti rotamer of the imino inhibitor form.     

Development of volatile profile of Kumpiak podlaski dry-cured ham during traditional ripening

Main aim of this research was to trace the development of volatile profile of Kumpiak podlaski dry-cured ham during traditional curing and ripening for 30 weeks. Volatiles were extracted from each 6-week period of ripening, and overall fifty-three aroma compounds were identified. Changes in chemical groups share between cured and fully ripened ham were observed: aldehydes (35.49 → 31.37%), ketones (25.18 → 14.62%), alcohols (17.97 → 15.74%), esters (3.37 → 12.04%), hydrocarbons (7.69 → 6.81%), fatty acids (0.02 → 0.53%), terpenes (2.26 → 9.70%) and heterocyclic aromatic compounds (0.99 → 0.78%). The 18th week of ripening is crucial for the aroma of Kumpiak podlaski ham due to start of continuous decrease in ketones and increase in esters’ and terpenes’ share. Formation of esters and terpenes originated from the presence of local herbs and the development of microflora. Principal component analysis (PCA) showed clear separation of samples from each 6-week period of ripening. Obtained results relying on thirty-seven compounds enabled to make a preliminary determination of ripening markers.     

Changes in the Physicochemical Properties of Blood and Skin Cell Membranes as a Result of Psoriasis Vulgaris and Psoriatic Arthritis Development

Psoriasis is accompanied by disturbed redox homeostasis, with systemic and local oxidative stress promoting the modification of basic components of cellular membranes. Therefore, the aim of the study was to investigate the effect of development of psoriasis vulgaris and psoriatic arthritis on the composition and physicochemical properties of skin cell membranes (keratinocytes and fibroblasts) and blood cells (lymphocytes, granulocytes and erythrocytes). Both forms of psoriasis are characterized by decreased levels and changes in the localization of membrane phospholipids, and an increased level of sialic acid as well as the lipid peroxidation product (malondialdehyde), which resulted in an increase in the zeta potential of skin cells and blood cells, with granulocytes and lymphocytes affected more than erythrocytes. Using theoretical equations and the dependence of the cell membrane surface charge density as a function of pH, it was shown that patients with psoriatic arthritis have a greater increase in the concentration of negatively charged groups on the membrane surface and reduced the value of the association constant with H⁺ compared to patients with psoriasis vulgaris. Therefore, it can be suggested that the physicochemical parameters of membranes, skin and blood cells, especially lymphocytes, can be used to assess the severity of the disease.     

Laboratory Full-Scale Comparative Tests of Rigid and Flexible Foundations of Buried Steel Structures

International Journal of Steel Structures - The technical issues described in the article concern the aspects of the implementation of foundations for buried flexible steel structures. The...