Scaling of compression strength in disordered solids: metallic foams

The scaling of compression strength with porosity for aluminium foams was investigated. The Al 99.96, AlMg1Si0.6 and AlSi11Mg0.6 foams of various porosity, sample size with and without surface skin were tested in compression. It was observed that the compression strength of aluminium foams scales near the percolation threshold with Tf ? 1.9 - 2.0 almost independently on the matrix alloy, sample size and presence of surface skin. The difference of the obtained values of Tf to the theoretical estimate of Tf = 2.64 ± 0.3 by Arbabi and Sahimi and to Ashby estimate of 1.5 was explained using an analogy with the Daoud and Coniglio approach to the scaling of the free energy of sol-gel transition. It leads to the finding that, there are two different universality classes for the critical exponent Tf: when the stretching forces dominate Tf = f = 2.1, respectively when bending forces prevail Tf = ?.d = 2.64 seems to be valid. Another possibility is the validity of relation Tf ? f which varies only according to the universality class of modulus of elasticity in foam

Intercalated theophylline-smectite hybrid for pH-mediated delivery

On the basis of their large specific surface areas, high adsorption and cation exchange capacities, swelling potential and low toxicity, natural smectite clays are attractive substrates for the gastric protection of neutral and cationic drugs. Theophylline is an amphoteric xanthine derivative that is widely used as a bronchodilator in the treatment of asthma and chronic obstructive pulmonary disease. This study considers the in vitro uptake and release characteristics of the binary theophylline-smectite system. The cationic form of theophylline was readily ion exchanged into smectite clay at pH 1.2 with a maximum uptake of 67±2 mg g−1. Characterisation of the drug-clay hybrid system by powder X-ray diffraction analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry and scanning electron microscopy confirmed that the theophylline had been exclusively intercalated into the clay system in an amorphous form. The drug remained bound within the clay under simulated gastric conditions at pH 1.2; and the prolonged release of approximately 40% of the drug was observed in simulated intestinal fluid at pH 6.8 and 7.4 within a 2-h timeframe. The incomplete reversibility of the intercalation process was attributed to chemisorption of the drug within the clay lattice. These findings indicate that smectite clay is a potentially suitable vehicle for the safe passage of theophylline into the duodenum. Protection from absorption in the stomach and subsequent prolonged release in the small intestine are advantageous in reducing fluctuations in serum concentration which may impact therapeutic effect and toxicit

SLOVAKIA. Critical junctures in the media transformation process.

In Slovakia, we record several critical junctures in the years 2000 – 2020, which had a significant impact on the media development, as well as on the opportunities and risks for deliberative communication and democracy. These included the advent of online media after 2000, the rise of social media since 2004, the worldwide economic crisis in 2008, the corruption case ‘Gorilla’ in 2011, the murder of the investigative journalist Ján Kuciak in 2018 and the COVID-19 pandemic since 2020. These events also affected the individual domains studied in Slovakia. Within the legal and ethical regulation, there are laws and standards that guarantee freedom of the press and the conduct of journalists is governed by multiple ethical codes. However, the most significant risks for the media in the journalistic domain are political influences and the pressures from media owners. These issues were also reflected in the decline in media credibility, as confirmed by research in the domain of media usage patterns. A rather positive phenomenon is, despite the persistent absence of empirical data that would support the claim, a sufficient number of academics who deal with the media competencies of media users. In summary, solid conditions (legislative, ethical, educational) for the media have been created in Slovakia, but the influences of politicians and media owners, job instability and poor financial evaluation of journalists remain a risk

SLOVAKIA. Risks and Opportunities Related to Media and Journalism Studies (2000–2020). Case Study on the National Research and Monitoring Capabilities.

Slovakia with a population of 5.3 million is one of the smaller countries in the Mediadelcom project, so the authors were able to identify and describe almost all relevant publications that contributed to the scholarly reflection on the four media domains in 2000 – 2020. The researchers mapped 865 publications, which included 707 academic and 159 non-academic outputs. Within the academic outputs, the project participants found that the most represented are academic articles, then academic books and finally academic book chapters. Most publications are written in Slovak and then in English. A smaller part of the body of literature is indexed in WoS or Scopus databases. Within the non-academic outputs, the project participants found that nonacademic articles, books and research reports have the largest representation. Most outputs are published in Slovak and without indexing in WoS or Scopus databases. Based on these findings, the authors claim that the media studies field has a well-established tradition in Slovakia, which is constantly evolving