INFLUENCE OF PACKAGING PROCESS ON MECHANICAL CHARACTERISTICS OF THE FLEXIBLE PACKAGING MATERIALS

The paper aimed to examine if the mechanical characteristics (tensile strength, elongation, and friction) of the selected flexible packaging materials (BOPP and PET/PE) change after the packaging process. Some researchers have shown that mechanical characteristics can change because of the various effects to which foils are exposed (temperature, transport devices, solvents, etc.). The measurement of tensile strength and elongation was carried out according to SRPS G.S2.734, and the measurement of friction according to ASTM D 1894. The results show that there were no significant changes in the examined mechanical characteristics that could affect the functionality of the packaging

Multicriteria evaluation of flexible packaging materials and the influence of printing and packaging process on their characteristics

Disertacija obuhvata deo relativno neistražene teme uticaja procesa štampanja i pakovanja na karakteristike štampanih fleksibilnih ambalažnih materijala, kao i određivanja njihovih vrednosti primenom odgovarajućih višekriterijumskih metoda vrednovanja. Na primeru ispitivanja i analize eksperimentalnih uzoraka fleksibilnih ambalažnih materijala, vrednovane su i poređene njihove veličine promena. Kod istraživanja i vrednovanja postavljena su ograničenja koja se pre svega odnose na odabrane vrste ambalažnih materijala i vrstu pakovanog sadržaja. Rezultat ovakvog vrednovanja su transparentne sume vrednosti pojedinih varijanti štampanih fleksibilnih ambalažnih materijala, gde se za svaki materijal može izračunati kvalitet ispunjenja zahteva za pojedine prehrambene proizvode

Applying and translating learning design and analytics approaches across borders

The Open University UK has been designing, implementing, and evaluating its OU Learning Design Initiative (OULDI) for over 15 years. Since 2015 a range of learning analytics (LA) studies and practical intervention studies have shown that these learning design (LD) decisions made by educators substantially influence what, how and when students are learning. However, applying and translating OULDI and LA in other institutions and borders is not a mere copy-paste job, and over the years OULDI been adopted and refined in a range of institutions. In this contribution we aim to reflect on how the principles and practical approaches of OULDI and LA need to be adjusted to fit other institutions and approaches. In several EU projects working with 64 practitioners from ten institutions from nine countries, University of Zagreb has critically reflected on the OULDI approach as well as other LD approaches, and altered several substantial elements in a newly designed Balanced Design Planning (BDP) approach. The lessons learned of applying and translating LD and LA approaches could help to inform educators how to use existing LD and LA approaches and adapt them to their institutional needs

Relevance of the diastereotopic ligation of magnesium atoms of chlorophylls in Photosystem I

The central magnesium (Mg) atoms of natural occurring tetrapyrroles such as chlorophylls (Chls) and bacteriochlorophylls (BChls) are typically five-coordinated, a fact which leads to the formation of diastereoisomers if the Mg-ligand bond is stable on the time scale of the observation method. This possibility has only been briefly addressed before in a CD-study of BChl c aggregates [T.S. Balaban A.R. Holzwarth, K. Schaffner, J. Mol. Struct. 349 (1995) 183]. On the basis of the chlorophyll-protein complex photosystem I (PSI), which has recently been characterized by single crystal crystallography [P. Jordan, P. Fromme, H.T. Witt, O. Klukas, W. Saenger, N. Kraubeta, Nature 411 (2001) 909], we find that chlorophyll a molecules are much more frequently bound by the protein matrix from one side (anti) than the other one (syn) in a ratio of 82:14, which corresponds to a significant DeltaDeltaG value of 4.3 kJ/mol. Syn and anti denote the orientation of the Mg-ligand with respect to the 17-propionic acid esterified by phytol. Furthermore, by parallel sequence analysis we find that the binding sites for both syn and anti chlorophylls have been strongly conserved during evolution-a fact which stresses the nonrandom manner in which chlorophylls are bound by the apoprotein in antenna complexes, in order to exert efficiently their light harvesting function and energy tunnelling. Most remarkably, all the syn chlorophylls are part of the inner core antenna system. Results from semiempirical quantum mechanical and detailed exciton coupling calculations allow us to speculate on the functional relevance of the diasteretopicity for PSI functioning. (C) 2002 Elsevier Science B.V. All rights reserved

Phenotypic variation of salmonella in host tissues delays eradication by antimicrobial chemotherapy

Antibiotic therapy often fails to eliminate a fraction of transiently refractory bacteria, causing relapses and chronic infections. Multiple mechanisms can induce such persisters with high antimicrobial tolerance in vitro, but their in vivo relevance remains unclear. Using a fluorescent growth rate reporter, we detected extensive phenotypic variation of Salmonella in host tissues. This included slow-growing subsets as well as well-nourished fast-growing subsets driving disease progression. Monitoring of Salmonella growth and survival during chemotherapy revealed that antibiotic killing correlated with single-cell division rates. Nondividing Salmonella survived best but were rare, limiting their impact. Instead, most survivors originated from abundant moderately growing, partially tolerant Salmonella. These data demonstrate that host tissues diversify pathogen physiology, with major consequences for disease progression and control