Cation-exchange properties of sediments in the Central depression of the Barents Sea

The article presents data on the study of cation exchange properties of sediments in the Central depression of the Barents Sea relative to heavy metals. The experiments were carried out both on sediments of natural moisture and on sediments after removal of sludge water. The maximum values of the equilibrium exchange capacity of sediments containing and not containing silt water practically coincide and are (in mg-eqv/g) in Mn, Ni, Zn, Cd – 0.20-0.28; Pb – 0.28-0.40; Cu – 0.36-0.66. According to the obtained values of the exchange capacity of precipitation belong to the class of adsorbents. The influence of sediments size and concentration of metal salt solutions on the exchange capacity of precipitation was studied. It is concluded that, on the one hand, precipitation contributes to the circulation of heavy metal cations in the marine environment, on the other hand, sediments can be considered as cleaners and pollutants of marine waters.

Biochemical characterization of a human septin octamer

Septins are part of the cytoskeleton and polymerize into non-polar filaments of heteromeric hexamers or octamers. They belong to the class of P-loop GTPases but the roles of GTP binding and hydrolysis on filament formation and dynamics are not well understood. The basic human septin building block is the septin rod, a hetero-octamer composed of SEPT2, SEPT6, SEPT7, and SEPT9 with a stoichiometry of 2:2:2:2 (2-7-6-9-9-6-7-2). Septin rods polymerize by end-to-end and lateral joining into linear filaments and higher ordered structures such as rings, sheets, and gauzes. We purified a recombinant human septin octamer from E. coli for in vitro experimentation that is able to polymerize into filaments. We could show that the C-terminal region of the central SEPT9 subunit contributes to filament formation and that the human septin rod decreases the rate of in vitro actin polymerization. We provide further first kinetic data on the nucleotide uptake- and exchange properties of human hexameric and octameric septin rods. We could show that nucleotide uptake prior to hydrolysis is a dynamic process and that a bound nucleotide is exchangeable. However, the hydrolyzed gamma-phosphate is not released from the native protein complex. We consequently propose that GTP hydrolysis in human septins does not follow the typical mechanism known from other small GTPases.

Secure MQTT PUF-Based Key Exchange Protocol for Smart Healthcare

Replay and eavesdropping attacks threaten the information security that is held by smart healthcare devices. An authenticated key exchange method to provide cryptography sessions is the best way to provide information security and secure authentication. However, smart healthcare devices do not have sufficient computation to perform heavy cryptography processes due to the limitations of the embedded devices used. We propose an authenticated key exchange protocol based on a physical unclonable function (PUF). The proposed protocol aimed to countermeasure from replay and eavesdropping attacks. We designed our protocol with one handshake process and three authentication processes. We evaluated our proposed protocol using Tamarin Prover. From the results of the evaluation, our proposed protocol can exchange properties correctly between communication actors and is valid in proving each lemma in eavesdropping and replay attacks.

Bio-Based Hydrogels With Ion Exchange Properties Applied to Remove Cu(II), Cr(VI), and As(V) Ions From Water

Hydrogels with ion exchange properties were synthesized from compounds derived from wood biopolymer hemicellulose and from commercial vinyl monomers to be tested as active materials for the removal of Cu(II), Cr(VI), and As(V) ions. The hemicellulose O-acetyl galactoglucomannan (GGM) was used as the precursor material, and through a transesterification reaction, GGM was converted into a macromonomer GGM–glycidyl methacrylate (GGM-GMA). Subsequently, the GGM-GMA macromonomer, containing more than one methacrylate group, was used as a crosslinking agent in the synthesis of hydrogels through free-radical polymerization reactions in combination with a 2-acrylamido-2-methyl-1-propanesulfonic acid monomer to produce a cation exchange hydrogel. Also, (3-acrylamidopropyl)trimethylammonium chloride monomer was applied together with the GGM-GMA to form hydrogels that can be used as anion exchange hydrogel. The hydrogels were characterized by Fourier transform-infrared (FT-IR), 1H-NMR spectroscopy, and thermogravimetric analysis (TGA), as well as derivative thermogravimetry (DTG). The microstructure of the hydrogels was characterized by scanning electron microscopy (SEM) analysis with X-ray microanalysis energy-dispersive spectroscopy (EDS). The results obtained regarding the absorption capacity of the Cu(II), Cr(VI), and As(V) ions were studied as a function of the pH value and the initial concentration of the metal ions in the solutions. Absorption was carried out in consecutive batches, and it was found that the poly(GGM-GMA/AMPSH) hydrogel reached an absorption capacity of 90 mg g–1 for Cu(II). The poly(GGM-GMA/APTACl) hydrogel reached values of 69 and 60 mg g–1 for Cr(VI) and As(V) oxyanions, respectively. Tests with polymer blends (mixtures of anionic and cationic hydrogels) were also carried out to remove Cu(II), Cr(VI), and As(V) ions from multi-ionic solutions, obtaining satisfactory results.