Adsorption of organic acids on magnetite nanoparticles, pH-dependent colloidal stability and salt tolerance

The adsorption of different organic acids and their influence on the pH-dependent charging, salt tolerance and so the colloidal stability of magnetite nanoparticles are compared. Adsorption isotherms of citric acid - CA, gallic acid - GA, poly(acrylic acid) - PAA, poly(acrylic-co-maleic acid) - PAM and humic acid - HA were measured. The pH-dependent charge state of MNPs was characterized by electrophoretic mobility and their aggregation by dynamic light scattering. The salt tolerance was tested in coagulation kinetic experiments. Although the adsorption capacities, the type of bonding (either H-bonds or metal ion-carboxylate complexes) and so the bond strengths are significantly different, the following general trends have been found. Small amount of organic acids at pH. <. ~8 (the pH of PZC of magnetite) - relevant condition in natural waters - only neutralize. s the positive charges, and so promotes the aggregation and sedimentation of nanoparticles. Greater amounts of organic acid, above the charge neutralization, cause the sign reversal of particle charge, and at high overcharging promote stabilization and dispersing. The thicker layer of PAA, PAM and HA provides better electrosteric stability than CA and GA. GA undergoes surface polymerization, thereby improving stabilization. The organic acids studied here eliminate completely the pH sensitivity of amphoteric magnetite, but only the polyanionic coverage provides significant increase in resistance against coagulating effects of salts at neutral pH commonly prevailing in natural waters

Comparison of clinical characteristics of patients with pandemic SARS-CoV-2-related and community-acquired pneumonias in Hungary – a pilot historical case-control study

The distinction between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)–related and community-acquired pneumonias poses significant difficulties, as both frequently involve the elderly. This study aimed to predict the risk of SARS-CoV-2-related pneumonia based on clinical characteristics at hospital presentation. Case-control study of all patients admitted for pneumonia at Semmelweis University Emergency Department. Cases (n = 30) were patients diagnosed with SARS-CoV-2-related pneumonia (based on polymerase chain reaction test) between 26 March 2020 and 30 April 2020; controls (n = 82) were historical pneumonia cases between 1 January 2019 and 30 April 2019. Logistic models were built with SARS-CoV-2 infection as outcome using clinical characteristics at presentation. Patients with SARS-CoV-2-related pneumonia were younger (mean difference, 95% CI: 9.3, 3.2–15.5 years) and had a higher lymphocyte count, lower C-reactive protein, presented more frequently with bilateral infiltrate, less frequently with abdominal pain, diarrhoea, and nausea in age- and sex-adjusted models. A logistic model using age, sex, abdominal pain, C-reactive protein, and the presence of bilateral infiltrate as predictors had an excellent discrimination (AUC 0.88, 95% CI: 0.81–0.96) and calibration (p = 0.27–Hosmer-Lemeshow test). The clinical use of our screening prediction model could improve the discrimination of SARS-CoV-2 related from other community-acquired pneumonias and thus help patient triage based on commonly used diagnostic approaches. However, external validation in independent datasets is required before its clinical use

Tapasztalatok es motiváltság: magyar középiskolások véleménye az egészségvédő programokról.

INTRODUCTION: Health-related attitudes can be encouraged most effectively at young ages. Young generations would require more interactive methods in programs engaged in health promotion. AIM: The aim of the authors was to get an insight into the attitudes, experience and motivation of youngsters in connection with health promotion programs and the community service work. METHOD: The questionnaires were filled in by high school students studying in Budapest and in the countryside (N = 898). RESULTS: 44.4% of the students did not have lessons or extracurricular activities dealing with health promotion. Concerning health promotion programs, youngsters in Budapest had more positive experience, while female students showed a more adoptive attitude. CONCLUSIONS: It was concluded that in one of the most susceptible life stages, many youngsters either do not participate in programs dealing with health promotion, or participate in programs that are within the framework of school subjects or extracurricular activities building on traditional teaching methods. Orv. Hetil., 2016, 157(2), 65-69

Polyisobutylene—New Opportunities for Medical Applications

This paper presents the results of the first part of testing a novel electrospun fiber mat based on a unique macromolecule: polyisobutylene (PIB). A PIB-based compound containing zinc oxide (ZnO) was electrospun into self-supporting mats of 203.75 and 295.5 g/m2 that were investigated using a variety of techniques. The results show that the hydrophobic mats are not cytotoxic, resist fibroblast cell adhesion and biofilm formation and are comfortable and easy to breathe through for use as a mask. The mats show great promise for personal protective equipment and other applications

Designed polyelectrolyte shell on magnetite nanocore for dilution-resistant biocompatible magnetic fluids.

Magnetite nanoparticles (MNPs) coated with poly(acrylic acid-co-maleic acid) polyelectrolyte (PAM) have been prepared with the aim of improving colloidal stability of core-shell nanoparticles for biomedical applications and enhancing the durability of the coating shells. FTIR-ATR measurements reveal two types of interaction of PAM with MNPs: hydrogen bonding and inner-sphere metal-carboxylate complex formation. The mechanism of the latter is ligand exchange between uncharged -OH groups of the surface and -COO(-) anionic moieties of the polyelectrolyte as revealed by adsorption and electrokinetic experiments. The aqueous dispersion of PAM@MNP particles (magnetic fluids - MFs) tolerates physiological salt concentration at composition corresponding to the plateau of the high-affinity adsorption isotherm. The plateau is reached at small amount of added PAM and at low concentration of nonadsorbed PAM, making PAM highly efficient for coating MNPs. The adsorbed PAM layer is not desorbed during dilution. The performance of the PAM shell is superior to that of poly(acrylic acid) (PAA), often used in biocompatible MFs. This is explained by the different adsorption mechanisms; metal-carboxylate cannot form in the case of PAA. Molecular-level understanding of the protective shell formation on MNPs presented here improves fundamentally the colloidal techniques used in core-shell nanoparticle production for nanotechnology applications