Calcium aluminate cement in castable alumina: From hydrate bonding to the in situ formation of calcium hexaluminate

Calcium hexaluminate (CA₆) is an intrinsically densification-resistant material, therefore, its porous structures are key materials for applications as high-temperature thermal insulators. This article reports on the combination of calcined alumina and calcium aluminate cement (CAC) in castable aqueous suspensions for the in situ production of porous CA₆. The CAC content (10–34 vol%) and the curing conditions ensure structural integrity prior to sintering and maximize the development of hydrated phases. Changes in physical properties, crystalline phases, and microstructure were investigated after isothermal treatments (120–1500 °C), and three sequential porogenic events were observed. The hydration of CAC preserved the water-derived pores (up to 120 °C), and the dehydroxylation of CAC hydrates (250–700 °C) generated inter-particles pores. Moreover, the in situ expansive formation of CA₂ and CA₆ (900–1500 °C) hindered densification and generated intra-particle pores. Such events differed from those observed with other CaO sources, and resulted in significantly higher pores content and lower thermal conductivity.     

Hydrolytic degree and antioxidant activity of purified casein characterised by different haplotypes (αs1-, β- and k-casein) after enzymatic hydrolysis with pepsin and enzymatic extract from Pleurotus eryngii

The aim of this study was to estimate the hydrolytic degree and antioxidant activity of purified casein characterised by different haplotypes (α_s1-, β- and k-casein) after in vitro digestion with two different enzymatic systems: pepsin from porcine gastric mucosa (EP) and a crude enzymatic extract from the edible mushroom Pleurotus eryngii. The used enzymes showed a different mode of casein catalysis with a consequent production of peptides of different antioxidant activity. The CN haplotype significantly influenced peptides production; in fact, the amino acid substitutions caused by genetic polymorphisms at the α_s1-, β- and k-CN loci influenced the sites of enzymatic cleavage and therefore the produced peptides. The above is evidenced by the different antioxidant activity found in the hydrolysates depending on the used enzymatic system, the CN haplotype, and the CN haplotype × enzymatic treatment interaction. The findings of this study are a perspective for the production of specific foods that exert a biological effect in addition to the nutritional one.     

AXL Receptor in Breast Cancer: Molecular Involvement and Therapeutic Limitations

Breast cancer was one of the first malignancies to benefit from targeted therapy, i.e., treatments directed against specific markers. Inhibitors against HER2 are a significant example and they improved the life expectancy of a large cohort of patients. Research on new biomarkers, therefore, is always current and important. AXL, a member of the TYRO-3, AXL and MER (TAM) subfamily, is, today, considered a predictive and prognostic biomarker in many tumor contexts, primarily breast cancer. Its oncogenic implications make it an ideal target for the development of new pharmacological agents; moreover, its recent role as immune-modulator makes AXL particularly attractive to researchers involved in the study of interactions between cancer and the tumor microenvironment (TME). All these peculiarities characterize AXL as compared to other members of the TAM family. In this review, we will illustrate the biological role played by AXL in breast tumor cells, highlighting its molecular and biological features, its involvement in tumor progression and its implication as a target in ongoing clinical trials.     

Influence of the gasket materials on the clamping pressure distribution in a PEM water electrolyzer: Bolt torques and operation mode in pre-conditioning

To keep optimally connected, all electrolysis cell elements is one of the most important design criteria. The optimal distribution of the clamping points is crucial to increasing cell performance. In this work, the compression pressure distribution inside of a 25 cm² PEM electrolysis cell was evaluated, using different materials: Teflon®, Viton®, ethylene propylene diene monomer rubber (EPDM), and nitrile rubber. Sealing material evaluation was performed taking as performance indicators: total compressed area (%) and compression pressure, for different torques applied. Pressure distribution was obtained by using pressure-sensitive films, analyzing the distribution of pressure points from three-dimensional plots (3D), and quantifying intensities of the images obtained. Results showed that pressure points distribution depends on the stiffness and thickness of the gasket materials. For a tightening torque of 3.70 N m, a pressure of 2.23 MPa is obtained with 85% of the membrane area compressed using nitrile rubber-EPDM gaskets.     

From linear temporal logic and limit-deterministic Büchi automata to deterministic parity automata

Controller synthesis for general linear temporal logic (LTL) objectives is a challenging task. The standard approach involves translating the LTL objective into a deterministic parity automaton (DPA) by means of the Safra-Piterman construction. One of the challenges is the size of the DPA, which often grows very fast in practice, and can reach double exponential size in the length of the LTL formula. In this paper, we describe a single exponential translation from limit-deterministic Büchi automata (LDBA) to DPA and show that it can be concatenated with a recent efficient translations from LTL to LDBA to yield a double exponential, ‘Safraless’ LTL-to-DPA construction. We also report on an implementation and a comparison with other LTL-to-DPA translations on several sets of formulas from the literature.

     

Synthesis and characterization of a pyrochlore solid solution in the Na2O-Bi2O3-TiO2 system

The compositional limits of a previously reported (J. Am. Ceram. Soc., 61, 5-8. (1978)) but relatively unstudied sodium-bismuth titanate pyrochlore solid solution are revised and their electrical properties presented. The pyrochlore solid solution we report forms via a different mechanism to that originally reported and occurs in a different location within the Na₂O-Bi₂O₃-TiO₂ ternary system. In both cases, relatively large amounts of vacancies are required on the A-sites and on the oxygen sites, similar to that reported for undoped ‘Bi₂Ti₂O₇’ pyrochlore. In contrast to ‘Bi₂Ti₂O₇’, this ternary pyrochlore solid solution can be prepared and ceramics sintered using conventional solid-state methods; however, the processing requires several challenges to be overcome to obtain dense ceramics. This cubic pyrochlore series has low electrical conductivity (and does not exhibit any evidence of oxide-ion conduction) and exhibits relaxor ferroelectric behavior with a broad permittivity maximum of ~100 near room temperature. Variable temperature neutron diffraction data do not provide any conclusive evidence for a phase transition in the pyrochlore solid solution between ~4 and 873 K.     

HPLC-fluorescence detection and adsorption of bisphenol A, 17beta-estradiol,and 17alpha-ethynyl estradiol on powdered activated carbon

The adsorption of three estrogenic compounds (bisphenol A (BPA), 17beta-estradiol (E2), and 17alpha-ethynyl estradiol (EE2)) on several powdered activated carbons (PAC) was investigated. Without preconcentration, method detection limits (MDL) using high-performance liquid chromatography (HPLC) with fluorescence detection at an excitation wavelength of 280 nm and an emission wavelength of 310 nm were 0.88, 1.15, and 0.96 nM for BPA, E2, and EE2, respectively. Compound recoveries were >90% in raw drinking water matrices. PAC screening studies (six PAC brands) indicated all three compounds were removed by PAC, but the percentage removal ranged from 31% to >99% based upon PAC type/dosage and presence/absence of natural organic matter. The order of removal (E2>EE2>BPA) corresponded with logK(ow) values for the compounds (3.1-4.0, 3.7-3.9, 3.3, respectively). Kinetic and PAC dose-response experiments were conducted with the two best performing PACs. Increasing contact time and PAC dose improved compound removal. Freundlich isotherm parameters were fit to the experimental data. This study confirms that PAC treatment is feasible for >99% removal of three estrogenic compounds from raw drinking waters that may be at risk for containing such compounds, at least at initial concentration of 500 ng/l and higher.     

Characterization of CVD Bonded Tyranno® Fibers Oxidized at High Temperatures

The oxidation of highly porous ceramic matrix composites (PCMCs) based on different Tyranno^® fibers has been analyzed by means of thermogravimetry and electron microscopy. Both uncoated fibers and PCMC materials exhibit parabolic kinetics between 900°C and 1250°C, these being faster for Ti‐doped than for Zr‐doped Tyranno fibers. Oxide layers in Ti‐doped fibers are porous and partially crystalline, whereas in Zr‐doped materials a significant fraction of relatively coarse β‐SiC grains is still found embedded in the amorphous silica matrix. On the other hand, the CVD‐SiC coatings exhibit higher oxidation rates from the outer surface than from the inner one, a phenomenon that has been associated not only with the more difficult access of oxygen to the inner face but also with the highly <111>  textured structure of these coatings, for which very different oxidation rates have been published for the inward and outward directions. Cracking phenomena observed above 1100°C for long dwelling times do not lead to an acceleration of the oxidation process, which could be due to the simultaneous crystallization of the amorphous silica layers.