A Review of Studies on the Covid-19 Pandemic and the Psychological Effects of Related Measures on Children, Youth and Parents. / COVID-19 Küresel Salgini ve Ilgili Tedbirlerin Çocuklar, Gençler ve Ebeveynler Üzerindeki Psikolojik Etkilerine Dair Çalismalarin Gözden Geçirilmesi.

Pandemics are social events that affect individuals' lives in many ways and have a significant impact on the mental health of masses. Pandemics and measures taken to combat these epidemics affect children and young people as well as adults. The purpose of the current review is to compile studies that have been conducted on the psychological effects of the COVID-19 pandemic and related measures on children, youth, and parents, and use the findings to shed light on future studies. In this review, 35 studies that were determined as a result of a comprehensive search in relevant literature were examined. It was observed that the aforementioned studies noted that the COVID-19 global pandemic and the measures taken to combat the epidemic (e.g., quarantine, lockdown, and school closures) had negative psychological effects on children, young people, and parents. Problems observed in children and young people, such as the fear of catching or transmitting the virus, getting bored, not being able to communicate enough with friends and teachers, and problems observed in parents, such as the troubles of negative repercussions of working at home or unemployment and difficulties in communicating with children with the closure of schools, are only a few to name these negative effects. The reviewed studies were discussed taking their limitations into account. Recommendations were made for future studies and intervention programs to be planned for community mental health. Keywords: COVID-19, children and youth, parents, pandemic, quarantine.

Dynamic nuclear polarization of spherical nanoparticles.

Spherical silica nanoparticles of various particle sizes (~10 to 100 nm), produced by a modified Stoeber method employing amino acids as catalysts, are investigated using Dynamic Nuclear Polarization (DNP) enhanced Nuclear Magnetic Resonance (NMR) spectroscopy. This study includes ultra-sensitive detection of surface-bound amino acids and their supramolecular organization in trace amounts, exploiting the increase in NMR sensitivity of up to three orders of magnitude via DNP. Moreover, the nature of the silicon nuclei on the surface and the bulk silicon nuclei in the core (sub-surface) is characterized at atomic resolution. Thereby, we obtain unique insights into the surface chemistry of these nanoparticles, which might result in improving their rational design as required for promising applications, e.g. as catalysts or imaging contrast agents. The non-covalent binding of amino acids to surfaces was determined which shows that the amino acids not just function as catalysts but become incorporated into the nanoparticles during the formation process. As a result only three distinct Q-types of silica signals were observed from surface and core regions. We observed dramatic changes of DNP enhancements as a function of particle size, and very small particles (which suit in vivo applications better) were hyperpolarized with the best efficiency. Nearly one order of magnitude larger DNP enhancement was observed for nanoparticles with 13 nm size compared to particles with 100 nm size. We determined an approximate DNP penetration-depth (~4.2 or ~5.7 nm) for the polarization transfer from electrons to the nuclei of the spherical nanoparticles. Faster DNP polarization buildup was observed for larger nanoparticles. Efficient hyperpolarization of such nanoparticles, as achieved in this work, can be utilized in applications such as magnetic resonance imaging (MRI).

Synthesis of silica nanoparticles covered with silver beads.

Procedures for producing silica nanoparticles suitable for further amino functionalization and subsequent decoration with silica beads were investigated in a comparative way. Several methods, one based on tetrapropylammonium hydroxide, the classical Stöber synthesis, and two with amino acids (either lysine or arginine) as catalysts were employed and followed by means of DLS, SAXS, and TEM. The amino acid methods proved to be by far the most satisfactory ones, yielding highly spherical and monodisperse nanoparticles with a tunable size range of 15-100 nm. The surface of the particles could be functionalized with propylamine, which enabled to obtain positive surface charge at low pH and to tune the zeta potential by the pH in the range of +/- 40 mV. Finally, the modified particles were used to reduce silver (I) ions at high pH, leading to the formation of very small silver beads covering the silica surface and yielding a nanocomposite with a "raspberry" structure. Interestingly, this could be achieved without using any complementary reducing agent besides the particles themselves, thereby opening a very simple path to the formation of composite metal containing colloidal systems.