Different route of hydroxide incorporation and thermal stability of new type of water clathrate : X-ray single crystal and Raman investigation

Chlormayenite Ca12Al14O32[♦4Cl2] (♦-vacancy) is partially hydrated micro porouss mineral with hydroxide groups situated at various crystallographic sites. There are few mechanisms describing its hydration. The first one assumes Cl- substitution by OH- at the center of the structural cages (W-site). The second one determines the converting a T1O4 tetrahedron to a T1O3(OH)3 octahedron due to the replacement of oxygen at the O2 site by three OH-groups according to the scheme: (O2O2- + W Cl-) → 3 × O2aOH. The third mechanism, not considered so far in the case of zeolite-like minerals, includes the hydroxide incorporation in form of hydrogarnet defect due to the arrangement of tetrahedral (OH)4 in vacant cages. This yields a strong hydrated phase containing even up to 35% of water more than in any currently known mineral applicable to Portland cement. Moreover, water molecules present in different structural cages are stable up to 355 K while dehydroxylation linked to the gradual loss of only 8% of OH- groups according to 3 O2aOH- → O2O2- + W OH- + gH2O occurs at temperature range from 355 K to 598 K

Temporal sequence of the human RBCs' vesiculation observed in nano-scale with application of AFM and complementary techniques

Based on the multimodal characterization of human red blood cells (RBCs), the link between the storage-related sequence of the nanoscale changes in RBC membranes in the relation to their biochemical profile as well as mechanical and functional properties was presented. On the background of the accumulation of RBCs waste products, programmed cell death and impaired rheological properties, progressive alterations in the RBC membranes including changes in their height and diameter as well as the in situ characterization of RBC-derived microparticles (RMPs) on the RBCs surface were presented. The advantage of atomic force microscopy (AFM) in RMPs visualization, even at the very early stage of vesiculation, was shown based on the results revealed by other reference techniques. The nanoscale characterization of RMPs was correlated with a decrease in cholesterol and triglycerides levels in the RBC membranes, proving the link between the lipids leakage from RBCs and the process of vesiculation

Surface Potential Driven Water Harvesting from Fog.

Access to clean water is a global challenge, and fog collectors are a promising solution. Polycarbonate (PC) fibers have been used in fog collectors but with limited efficiency. In this study, we show that controlling voltage polarity and humidity during the electrospinning of PC fibers improves their surface properties for water collection capability. We experimentally measured the effect of both the surface morphology and the chemistry of PC fiber on their surface potential and mechanical properties in relation to the water collection efficiency from fog. PC fibers produced at high humidity and with negative voltage polarity show a superior water collection rate combined with the highest tensile strength. We proved that electric potential on surface and morphology are crucial, as often designed by nature, for enhancing the water collection capabilities via the single-step production of fibers without any postprocessing needs

Surface potential and roughness controlled cell adhesion and collagen formation in electrospun PCL fibers for bone regeneration

Surface potential of biomaterials is a key factor regulating cell responses, driving their adhesion and signaling in tissue regeneration. In this study we compared the surface and zeta potential of smooth and porous electrospun polycaprolactone (PCL) fibers, as well as PCL films, to evaluate their significance in bone regeneration. The ' surface potential of the fibers was controlled by applying positive and negative voltage polarities during the electrospinning. The surface properties of the different PCL fibers and films were measured using X-ray photoelectron spectroscopy (XPS) and Kelvin probe force microscopy (KPFM), and the zeta potential was measured using the electrokinetic technique. The effect of surface potential on the morphology of bone cells was examined using advanced microcopy, including 3D reconstruction based on a scanning electron microscope with a focused ion beam (FIB-SEM). Initial cell adhesion and collagen formation were studied using fluorescence microscopy and Sirius Red assay respectively, while calcium mineralization was confirmed with energy-dispersive x-ray (EDX) and Alzarin Red staining. These studies revealed that cell adhesion is driven by both the surface potential and morphology of PCL fibers. Furthermore, the ability to tune the surface potential of electrospun PCL scaffolds provides an essential electrostatic handle to enhance cell-material interaction and cellular activity, leading to controllable morphological changes

Thermal stability of the solid DNA as a novel optical material

Deoxyribonucleic acid (DNA) has been extensively exploited for the past decade as the matrix material in organic electronics and nonlinear optics. In this work thermal stability of DNA in solid form was thoroughly studied, mainly by optical methods. Solid samples of low molecular mass DNA were subjected to heating according to different protocols and dissolved. The temperature effect was observed in the evolution of UV absorption and circular dichroism spectra. Thin films of DNA were deposited on polished silicon wafers. They were conditioned at consecutively raised temperature and simultaneously measured by spectroscopic ellipsometry. Changes in chemical composition of thermally treated films were studied by XPS. Below 100 $^{\circ}$C all thermal effects were reversible. Melting occurred at c.a.140 $^{\circ}$C. Irreversible chemical changes probably occurred at 170-180 $^{\circ}$C