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Many physical and chemical properties of solids, such as strength, plasticity, dispersibility, solubility and dissolution are determined by defects in the crystal structure. The aim of this work is to study in situ dynamic, dispersion, chemical, biological and surface properties of lacosamide powder after a complete cycle of mechanical loading by laser scattering, electron microscopy, FR-IR and biopharmaceutical approaches. The SLS method demonstrated the spontaneous tendency toward surface-energy reduction due to aggregation during micronisation. DLS analysis showed conformational changes of colloidal particles as supramolecular complexes depending on the loading time on the solid. SEM analysis demonstrated the conglomeration of needle-like lacosamide particles after 60 min of milling time and the transition to a glassy state with isotropy of properties by the end of the tribochemistry cycle. The following dynamic properties of lacosamide were established: elastic and plastic deformation boundaries, region of inhomogeneous deformation and fracture point. The ratio of dissolution-rate constants in water of samples before and after a full cycle of loading was 2.4. The lacosamide sample, which underwent a full cycle of mechanical loading, showed improved kinetics of API release via analysis of dissolution profiles in 0.1 M HCl medium. The observed activation-energy values of the cell-death biosensor process in aqueous solutions of the lacosamide samples before and after the complete tribochemical cycle were 207 kJmol−1 and 145 kJmol−1, respectively. The equilibrium time of dissolution and activation of cell-biosensor death corresponding to 20 min of mechanical loading on a solid was determined. The current study may have important practical significance for the transformation and management of the properties of drug substances in solid form and in solutions and for increasing the strength of drug matrices by pre-strain hardening via structural rearrangements during mechanical loading. [ABSTRACT FROM AUTHOR]

The issues of assessing the measurement error using laser coordinate measuring systems (LCMS) of the geometric parameters of vibrating, and also vibrating objects are considered. At the same time, attention is focused on their time-average values. In a number of special cases, calculated relations are given to estimate the average errors in measuring the amplitude and frequency of vibrations of the objects under consideration, their geometric parameters, such as the distance to the laser tracker, coordinates of points on the surface, and other indicators. It is noted that these ratios were obtained for the first time, therefore, in order to increase their reliability, it is possible to introduce them into the corresponding dependences of correcting coefficients and functions.

In solar cells, hybrid halide perovskites operate under constant bias, thus their stability towards electric field-induced degradation is of key importance. Here we report on evidence of previously unidentified electric field-induced transitions and degradation path of CH3NH3PbI3 (MAPbI3) using elemental and phase mapping. Thin films of MAPbI3 were deposited onto 1–2 µm-pitch interdigitated electrodes and subjected to direct current (DC)-polarization. The MAPbI3 layer polarized with < 0.8 V/µm DC electric field undergoes pronounced ion redistribution to methylammonium-rich MAPbI3−y (y < 0.6) and iodine-rich MA1−xPbI3 (x < 0.3) regions. Polarization-induced loss of both methylammonium and iodine provokes degradation of MAPbI3. Using nanofocus grazing-incidence wide-angle X-ray scattering (GIWAXS), we unambiguously showed that the bias voltage induces the transformation of β-MAPbI3 to metastable δ-MAPbI3 polymorph via alignment of polar organic cation with the electric field. This transformation is partially reversible upon field removal. However, once formed, δ-MAPbI3 disrupts the morphology of pristine film and undergoes decomposition to β-MAPbI3 (β-MAPI) and PbI2. With the aforementioned compositional and phase changes, only MA-rich part serves as the charge separation layer, while the I-rich excitation is blocked with the PbI2 barrier serving as holes trapping layer. These observations reveal the intermediate steps in electric-field-driven degradation of halide perovskites and show the role of polar cations in the process, which is instructive for further material design with higher stability metrics. [ABSTRACT FROM AUTHOR]

Abstract: We report on microsensor for direct detection of microorganisms in aerosol. Microsensor is based on interdigitated ultramicroelectrodes modified with electropolymerized 3‐aminophenylboronic acid (3‐APBA). Appearance of Penicillium chrysogenum in aerosol as well as further increase of its concentration lead to poly(3‐APBA) conductivity increase found by impedance spectroscopy. According to Raman spectroscopy data, the presence of microorganism affects polymer conductivity similarly to binding of glucose to polymer which results in self‐doping phenomenon. The elaborated detection technique is 100 times faster comparing to agar plate cultivation: it requires less than 20 minutes for analysis. Dynamic range of microsensor includes the upper limit for non‐contaminated air in Russian hygienic standard (500 colony‐forming units per cubic meter). The first reported reagentless detection of Penicillium chrysogenum in aerosol by conductivity increase reveals a prospect for creation of a promising alternative to conventional techniques for detection of microorganisms. [ABSTRACT FROM AUTHOR]

Abstract: We report on Prussian Blue based (bio)sensors displaying advantageous analytical performance characteristics when operated both in conventional three‐electrode regime powered by potentiostat and in power generation mode. ‘Self‐powered’ sensors are commonly aimed to produce sufficient energy for signalling and, thus, being energetically autonomous. In order to generate maximum energy output, the electrodes with high potential difference are preferable. In contrast, we propose the systems with the lowest potential difference between the working and the counter electrodes. Short‐circuiting the Prussian Blue modified working and the Ag|AgCl reference electrode, working electrode potential is adjusted to 0.00 V without potentiostat. The efficiency of the (bio)sensors in power generation mode is achieved due to high catalytic activity of Prussian Blue at 0.00 V versus Ag|AgCl reference. Here we discuss the benefits of the Prussian Blue based (bio)sensors operated through power generation in a short‐circuit regime without potentiostat, including an order of magnitude decreased noise and simplified readout. The multimodality of the sensors would provide their versatile functionality for the electroanalysis and elaboration of miniature highly sensitive wearable devices. [ABSTRACT FROM AUTHOR]

The ability of Prussian Blue, ferric hexacyanoferrate (FeHCF), to sensitively and selectively detect hydrogen peroxide by its reduction in the presence of oxygen is of high importance for analytical chemistry. Success with Prussian Blue (PB) provided an appearance of contradictory reports concerning electrocatalysis of the other transition metal hexacyanoferrates (HCFs) in H2O2 reduction. Investigating thermodynamics of the catalyzed reactions as well as electrochemical properties of the hexacyanoferrates, we are able to conclude that the noniron hexacyanoferrates themselves are completely electrocataryrically inactive, except for a minor electrocatalysis in the opposite reaction, hydrogen peroxide oxidation, registered for NiHCF. Concerning the most important reaction, H2O2 reduction, the observed electrocatalytic activity (by the way, 100 times decreased compared to PB) is due to the presence of FeHCF (Prussian Blue) as defects in the structure of noniron hexacyanoferrates. This finding, considering other unique properties of transition metal HCFs, will provide a systematic search for sensing materials with improved analytical performance characteristics. [ABSTRACT FROM AUTHOR]

This letter introduces the pre-steady-state kinetic approach, which is traditional for evaluation of elementary constants in molecular (enzyme) catalysis, for nanozymes. Apparently, the most active peroxidase-mimicking nanozyme based on catalytically synthesized Prussian Blue nanoparticles has been chosen. The elementary constants ( k 1 ) linearly decays with an increase of the substrate redox potential (cotangent value ≈125 mV). On the contrary, for the largest nanozymes with a diameter above 150 nm, k 1 ) linearly decays with an increase of the substrate redox potential (cotangent value ≈125 mV). On the contrary, for the largest nanozymes with a diameter above 150 nm, k 1 is almost independent of it. Moreover, for the substrate with the lowest redox potential (K 4 [Fe(CN) 6 ]), the rate constant under discussion ( k 1 ) is almost independent of the nanozymes' size. Perhaps, the rate of the intrananozyme electron transfer causing bleaching becomes comparative or even lower than that of the nanoparticle interaction with the fastest substrate. Anyway, the elementary constant of nanozyme reduction with potassium ferrocyanide ( k 1 ) reaches the value of 1 × 10 10 M -1 s -1 , which is 3-4 orders of magnitude faster than for enzymes peroxidases. The obtained results obviously demonstrate that the pre-steady-state kinetic approach is able to discover novel advantages of nanozymes from both fundamental and practical points of view.

We report on the kinetic mechanism of the catalytically synthesized Prussian Blue nanoparticles denoted as "artificial peroxidase". In contrast to the enzyme, whose active site first interacts with hydrogen peroxide forming the so-called Compound I, in the case of the nanozymes, H 2 O 2 oxidizes their complex with reducing substrate. Slow release of the product (oxidized form of the latter) from the nanozymes has been registered. The interaction of substrates with the nanozymes is 100 times faster than with enzyme peroxidases, and the rate-limiting constant for the nanozymes is also 2 orders of magnitude greater: for pyrogallol k 2 = 1.3 ± 0.1 × 10 8 M -1 s -1 and for ferrocyanide k 2 = 1.9 ± 0.1 × 10 8 M -1 s -1 . Thus, the discovered novel advantage of nanozymes over the corresponding enzymes is the 100-fold greater bimolecular rate constants, resulting, most probably, from their uniformly accessible surface, avoiding the effect of rotation on the diffusion-controlled rate.