A comprehensive experimental investigation and theoretical description of liquid-gas pervaporative transport across nanoporous membranes is presented. Anodic alumina and track-etched membranes, featuring straight channels within a diameter range of 25-200 nm, were experimentally tested in pervaporation of liquid water, alcohols and hydrocarbons at various operation conditions. The pivotal role of the equilibrium saturation pressure of penetrants (varied from similar to 10 to similar to 50,000 Pa) on the membranes performance was exposed, while no significant influence of neither channel diameters nor membrane thickness was revealed. Pervaporative flux, exceeding 1.510(-5) molm(-2)s(-1)Pa-1 (similar to 10 kgm(-2)h(-1)atm(-1) for water at 60 degrees C), surpasses Knudsen permeability of the membranes, indicating liquid transport driven by Laplace pressure. However, it lies far below the theoretical Hertz-Knudsen limit for evaporating menisci, revealing heat transfer limitation. The study rivals a substantial temperature drop, reaching 30 degrees C at the evaporation plane. That is proportional to the square root of the saturation pressure of penetrants, as revealed by experimental results and theoretical description. It results in transport limitation with heat supply to the evaporation menisci, constrained especially at the membrane interfaces. Strong cooling of the evaporative plane suppresses pervaporative flux with diminishing local saturation pressure of penetrants. The provided description provides low relative deviation (<30 %) within the whole set of penetrants and membrane microstructures. It was successfully utilized for improving stability of nanoporous membranes in desalination pervaporation with deposition of highly permeable thin graphene oxide and MXene selective addlayers. Composite membranes reveal a slight lowering of the performance compared to the nanoporous substrates, while having a greatly enhanced long-term stability in pervaporative desalination with ions rejection.

We report on the Prussian Blue (PB) and glucose oxidase (GOx) based first-generation biosensor with a linear calibration range remarkably extended to high concentrations, which is suitable for continuous monitoring in oxygen-deficient media. The increase of the apparent Michaelis constant by several orders of magnitude, resulting in a record linear range, was achieved by reduction of the GOx amount immobilized in the sensor membrane. The latter allowed one to diminish the O2 deficiency and keep its transport in pace with glucose oxidation. To compensate a predictable decrease in sensitivity, we suggested pulse power generation readout providing 100-fold response amplification. As a result, for the pulse-operated first-generation biosensors, the optimal linear range from 0.5 to 30 mM, high sensitivity (over 10 mA M-1 cm-2), extinguished dependence of the response on O2 content, and improved operational stability were achieved. Such characteristics allowed the adaptation of the PB based biosensors for glycemia control upon continuous in vivo monitoring of the interstitial fluid glucose.

Variation of water permeance and interlayer spacing of graphene oxide (GO) is traced with in-situ X-ray diffraction upon its heating/cooling in dry (-1000 Pa), humid (-100 % RH) air and liquid water. Reversible variation of GO interlayer distance ranging 8.3-7.2 a in dry air, 11-7.5 a in humid air and 13.9-12.4 a in liquid water is revealed in the temperature range of 25-80 degrees C. Accounting for GO layer thickness of -6 a it corresponds manifold alterations of slit width with temperature and water vapor pressure, resulting in over 3 orders of magnitude variation of membrane performance. A typical rise of the permeance of 300-500 % within the temperature range at constant humidity is contraposed to a miserable increase in the activation energy for H2O transport, revealing the decisive impact of slit sizes on GO performance. The effect is addressed to entropy-driven variation of water absorption heat with slit sizes in GO. Variation of interlayer spacing of -10 % was also exposed with thermal dissociation of GO groups and H+ migration to the interlayer space as supported by semiempirical calculations. Reversible structural changes in GO are successfully exploited for fabrication thermally switched membranes for dehumidification with initial permeance of -1.1 & sdot;10-6 mol m- 2 Pa- 1 & sdot;s- 1 and its variation over 50 % at supplied power of -500 W/m2.

Single-phase barium hexaferrite powders with crystallite sizes in a single-domain region and with the general composition BaFe12-xMnxO19, where x = 0, 2, 4, 6, were synthesized applying a citric sol-gel auto-combustion technique with final annealing temperatures of 900 - 1200 degrees C. The crystal structures were refined, and the magnetic properties were studied. The observed variations in atomic positions with the Mn-for-Fe substitution revealed presence of Mn in three oxidation state +2, +3, and +4, with a preference of Mn2+ to the tetrahedral 4f(1) site and Mn4+ to the octahedral 2a and 12k sites. With the Mn-doping, the samples' magnetization decreased, while coercivity increased and reached 8.4 kOe for x = 6. The rise of the annealing temperature resulted in a slight growth of magnetization with a general tendency of the coercivity to decrease. A Curie temperature decreased with the Mn-doping remaining above room temperature for the maximal doping.

We have synthesized highly anisotropic plate-like nanoparticles of aluminum-substituted strontium hexaferrite via the crystallization of 4Na2O x 9SrO x 5.5Fe2O3 x 4.5Al2O3 x 4B2O3 glass, achieving tunable sizes by adjusting the annealing temperature (650-750 degrees C). Particle sizes range from 39 nm x 4.5 nm to 90 nm x 7.1 nm. Aluminum substitution significantly increases the coercivity of the colloid particles up to 5600 Oe. These nanoparticles form stable aqueous colloids in the pH range of 2-4. The ferrofluids exhibit a strong "jalousie effect" of adjustable optical transmission in external magnetic fields. The transmission difference rises with increasing nanoplate diameter and anisotropy factor. The high remanence of the hexaferrite particles allows them to be manipulated by weak magnetic fields, providing high-frequency particle motion with available electromagnets. Tunable particle sizes facilitate specific applications: smaller particles offer higher relaxation frequencies and better stability, while larger particles provide superior light scattering and induced mechanical momentum. These properties make the nanoparticles suitable for microfluidic stirring, mechanical impacting for cancer treatment, high-frequency light modulation, optical probing of magnetic fields, and micrometer-scale viscoelasticity sensing. A method for producing highly anisotropic plate-like hexaferrite colloidal nanoparticles with tunable diameters is proposed.

Doping of the (Sr,Ba)10(PO4)6(OH)2 apatite ceramics with a small quantity of Dy2O3 was studied. Formation of the Dy3+ containing high-energy single-ion magnet (SIM) in the apatite structure was confirmed. Partial replacement of Ba for Sr in the structure resulted in a regular increase of the remagnetization energy barrier Ueff from 1043 to 1119 cm-1, while the solubility of Dy3+ in the compound dropped drastically. Ueff followed simple relations with the alkaline-earth metal cation size and the compound composition, highlighting predictability of SIM parameters.

Despite non-invasive instant monitoring of sweat metabolites is becoming a general trend in early diagnostics and screening, the reliability and accuracy of the on-skin electrochemical biosensors in real-life scenarios still remain questionable. As a rule, mass transport effects in scantily excreted liquids are ignored, when considering the design of such wearable setups. Here we provide a comprehensive investigation of the disruption factors for commonly used Prussian Blue based (bio)sensors under different hydrodynamic conditions (2 x 10-5 - 5 x 100 mm s-1 electrolyte velocity). A huge effect of flow on the (bio)sensors response has been revealed and explained with transport limitations for both analyte influx and reaction product outflux. It suggests no need for improving the sensor sensitivity, while minimizing analyte consumption and enhancing product withdrawal. Some strategies concerning measurement schemes and sensor design ensuring reliable sweat analysis have been discussed and illustrated for lactate and glucose on-skin monitoring.

A small amount of cobalt was incorporated into the lanthanum calcium silicate apatite structure by annealing at 1500 °C in argon. The compound exhibits easy-axis magnetic anisotropy with a zero-field splitting parameter 2D of −60 cm−1 and field- induced slow relaxation of magnetization with a remagnetization energy barrier of 58–63 cm−1. Thereby, for the first time, a cobalt-based single-ion magnet was created in silicate.

We propose pulse power generation (PPG) amperometry as an advanced readout realized for Prussian blue (PB)-based (bio)sensors. In contrast to the conventional power generation mode, when the current response is generated upon continuous short-circuiting, the suggested pulse regime is fulfilled by periodic opening and shorting of the circuit. Despite PB being electroactive, the pulse readout is advantageous over conventional steady-state power generation, providing up to a 15-fold increased signal-to-background ratio as well as dramatically improved sensitivity exceeding 10 A·M-1·cm-2 for H2O2 sensors and 3.9 A·M-1·cm-2 for glucose biosensors. Such analytical performance characteristics are, most probably, achieved due to the enrichment of the diffusion layer by analyte mass transfer from the bulk upon opening of the circuit. Due to an improved sensitivity-to-background ratio, reduced flow-rate dependence, and enhanced operational stability, the regime allows reliable monitoring of blood glucose variations through sweat analysis with the on-skin device.

We report on the simultaneous monitoring of sweat lactate concentration and sweat secretion rate. For this aim lactate oxidase-Prussian Blue enzyme-nanozyme type lactate biosensors were elaborated. The use of siloxaneperfluorosulfonated ionomer composite membrane for enzyme-nanozyme immobilization results in the biosensor displaying flux independence in the whole range of physiological sweat secretion rates (0.025-2 mu l cm(-2) min(-1)). On the contrary, current response of the biosensor based on solely siloxane membranes becomes saturated at physiological sweat lactate concentration, depending mostly on the flow rate. Accordingly, for simultaneous monitoring of sweat lactate concentration and its secretion rate both flow-through biosensors were integrated with high-accuracy wearable electronic devices allowing real-time remote monitoring. As found, during exhaustive physical exercise sweat secretion rate and lactate content are independent of each other, thus, confirming that this excretory liquid is suitable for non-invasive diagnostics.

Here, we report on the fabrication of light-switchable and light-responsive membranes based on graphene oxide (GO) modified with azobenzene compounds. Azobenzene and para-aminoazobenzene were grafted onto graphene oxide layers by covalent attachment/condensation reaction prior to the membranes’ assembly. The modification of GO was proven by the UV-vis, IR, Raman and photoelectron spectroscopy. The membrane’s light-responsive properties were investigated in relation to the permeation of permanent gases and water vapors under UV and IR irradiation. Light irradiation does not influence the permeance of permanent gases, while it strongly affected that of water vapors. Both switching and irradiation-induced water permeance variation is described, and they were attributed to over 20% of the initial permeance. According to in situ diffraction studies, the effect is ascribed to the change to the interlayer distance between the graphene oxide nanoflakes, which increases under UV irradiation to ~1.5 nm while it decreases under IR irradiation to ~0.9 nm at 100% RH. The last part occurs due to the isomerization of grafted azobenzene under UV irradiation, pushing apart the GO layers, as confirmed by semi-empirical modelling.

Structural ordering in the concentrated magnetic colloids containing 50 × 5 nm hard magnetic disc-like SrFe12O19 nanoparticles was investigated by cryogenic scanning electron microscopy, optical microscopy, magnetic measurements, and small-angle X-ray scattering. It was revealed that macroscopically homogeneous magnetic liquid consists of dynamic threads of stacked nanoparticles. The threads align into quasiperiodic arrays with the distances between individual threads of a few micrometers. They also can form pseudodomain structures with ~ 90° domain boundaries realized through T-type thread interconnects. The effects of magnetic attraction and electrostatic repulsion on the equilibrium interplatelet distance in the threads were studied. It was demonstrated that this distance can be tuned by the control of the particles charge and electric double layer screening from Stern layer thickness (~ 1 nm) to tens of nanometers. It was shown that the permanent magnetic field is not able to cause any structural changes in the ordered magnetic liquid phase, while alternating field draws particles apart by their vibrations. External variation of interparticle distance up to 6% was achieved using an alternating magnetic field of low intensity. Experimental data were complemented by the theoretical models of screened electrostatic interactions between spherical and platelike magnetic particles. The last model provides good predictive power and correlates with the experimental data. The stabilization energy of the condensed phase in the order of 1–10 kBT was derived from the model. An approach allows controlling of an equilibrium interparticle distance and interparticle distance distribution by adjusting the magnetization and surface charge of the particles as well as the ionic strength of the solvent.

New photocatalysts were synthesized from graphene oxide (GO) and zinc porphyrins via non-covalent self-assembly in Pickering emulsions. The formation of surface-attached metal organic frameworks (SURMOFs) with different size of mesopores (1.1. and 1.6 nm) was confirmed by X-ray powder diffraction and BET nitrogen absorption methods. The activity of the SURMOF/GO materials in photodegradation of rhodamine 6G (Rh6G) and 1,5-dihydroxynaphtalene (DHN) were studied spectroscopically. The photocatalysts initiate aerobic oxidative photodestruction with k up to 2.3 x 10(-1) min(-1) through generation of singlet oxygen on porphyrin centers. Under anaerobic conditions, these materials assist photoreduction of the same dyes in the SURMOF micmpores. The mechanisms of photodegradation assisted by SURMOF/GO hybrids were confirmed by a combination of MALDI-TOF spectroscopy, Sensor Green and terephthalic acid probing. The size of the SURMOF pores controls the reduction, which occur due to the effective charge separation between porphyrin SURMOFs and GO. The photocatalyst with larger pores can transform both Rh6G and DHN, whereas that one with smaller pores is active only with respect to small DHN molecules. The ability of as-formed SURMOF/GOs to exploit two mechanisms yielding different products of photodestruction provides a basis for creating novel ambivalent photocatalysts for selective transformations of targeted compounds in molecular mixtures.

Magnetically hard ferrites attract considerable interest due to their ability to maintain a high coercivity of nanosized particles and therefore show promising applications as nanomagnets ranging from magnetic recording to biomedicine. Herein, we report an approach to prepare nonsintered single-domain nanoparticles of chromium-substituted hexaferrite via crystallization of glass in the system SrO–Fe2O3–Cr2O3–B2O3. We have observed a formation of plate-like hexaferrite nanoparticles with diameters changing from 20 to 190 nm depending on the annealing temperature. We demonstrated that chromium substitution led to a significant improvement of the coercivity, which varied from 334 to 732 kA m−1 for the smallest and the largest particles, respectively. The results provide a new strategy for producing high-coercivity ferrite nanomagnets.

The assessment of the radiolytic stability of media is an important task in the fields of nuclear power engineering and radiochemistry. Such studies must be carried out in special laboratory conditions with the use of sources of ionizing radiation, which may increase personal doses of the staff. In addition, difficulties arise in studying the products of irradiated media. While it is impossible to abandon experiments to obtain reliable results in this area, computational methods of quantum chemistry can reduce the number of experiments and help understand the mechanisms of the reactions that occur during radiolysis. Here we would like to present a software shell of the Qb@ll program performing time-dependent density functional theory simulations of the radiolysis process.

Tb-diluted and Tb-rich apatite-type silicates with compositions Y7.75Tb0.25Ca2(SiO4)6O2 and Tb8Ca2(SiO4)6O2, respectively, exhibit field induced multiple slow relaxation of magnetization. The former reveals two slow relaxation paths, the latter only one with a longer relaxation time of several seconds. The relaxation features of the Tb-diluted one are comparable with those of analogue compounds, where Tb is replaced by Dy, as well as with those of a Tb-doped calcium phosphate apatite. The relaxation parameters of the Tb-rich compound virtually match those of the Dy-based analogue Dy8Ca2(SiO4)6O2. The latter represents the first instance of independence of magnetization relaxation on the nature of a paramagnetic rare-earth metal ion in single ion magnet like materials.

Spray deposition is a scalable and cost-effective technique for the fabrication of magnetic hybrid films containing diblock copolymers (DBCs) and magnetic nanoparticles. However, it is challenging to obtain spray-deposited anisotropic magnetic hybrid films without using external magnetic fields. In the present work, spray deposition is applied to prepare perpendicular anisotropic magnetic hybrid films by controlling the orientation of strontium hexaferrite nanoplatelets inside ultra-high-molecular-weight DBC polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films. During spray deposition, the evolution of DBC morphology and the orientation of magnetic nanoplatelets are monitored with in situ grazing-incidence small-angle X-ray scattering (GISAXS). For reference, a pure DBC film without nanoplatelets is deposited with the same conditions. Solvent-controlled magnetic properties of the hybrid film are proven with solvent vapor annealing (SVA) applied to the final deposited magnetic films. Obvious changes in the DBC morphology and nanoplatelet localization are observed during SVA. The superconducting quantum interference device data show that ferromagnetic hybrid polymer films with high coercivity can be achieved via spray deposition. The hybrid films show a perpendicular magnetic anisotropy before SVA, which is strongly weakened after SVA. The spray-deposited hybrid films appear highly promising for potential applications in magnetic data storage and sensors.

New computational framework has extended an inverse materials design over all the possible stoichiometric compounds.

Considerable attention has been paid recently to FeTe2O5Cl due to reduced dimensionality and frustration in the magnetic subsystem, succession of phase transitions, and multiferroicity. The efforts to grow its selenite sibling resulted in the mixed halide compound Fe(Te1.5Se0.5)O5Cl, which was found crystallizing in a different structural type and possessing properties drastically different from those of a parent system. Its magnetic subsystem features weakly coupled Fe3+-Fe3+ dimers showing the regime of short-range correlations at T-M similar to 70 K and long-range order at T-N = 22 K. In a magnetically ordered state, sizable spin-orbital interactions lead to a small canting of Fe3+ moments. Magnetic dipole-dipole interactions contribute significantly to the experimentally observed orientation of magnetization easy axis in the ac plane. The first principles calculations of leading exchange interactions were found in agreement with measurements of thermodynamic properties and Raman spectroscopy.