The lava plug in the crater of the Sarychev Peak volcano (Kuril Islands) was removed in June 2009 as a result of explosions that accompanied a strong eruption, and the crater-bottom elevation ...abruptly decreased thereafter. Based on satellite imagery and images taken during a helicopter overflight in 2016, the level of crater-bottom sinking was measured at about 190–220 m from the crater rim. The crater bottom had been stable up until autumn 2017, when it began to rise, as revealed from the satellite imagery. As of autumn 2019, the crater bottom has been uplifted by approximately 150 m. The crater volume filled during this rising is about 10 million m
3
. The cycles of subsidence and rising in the last 75 years were repeated three times with respect to every strong (considerable) eruption. The new period of rising probably indicates the preparation for a new, potentially dangerous eruptive event.
Multisoliton complexes have been generated in an active ring resonator with an L-shaped magnonic microwaveguide and a saturated amplifier. It has been shown that an irregular microwaveguide ...simultaneously supports both the propagation of magnetostatic spin waves with different (normal and anomalous) dispersion and competition between three- and four-wave spin-wave interactions. Generated multisoliton complexes consist of quasiperiodic sequences of two dark parametric pulses containing “soliton trains” consisting of three dark ultrashort four-wave envelope solitons. It has been found that quasiperiodic sequences of multisoliton complexes generated by the active ring resonator with a regular magnonic microwaveguide consist of one dark parametric pulse, which also contains three dark four-wave solitons. However, in contrast to the preceding case, four-wave solitons, having a longer duration, do not form soliton trains inside a dark parametric pulse.
To reveal conformational changes resulting in the formation of insulin fibrils, it is necessary to identify amyloidogenic regions in the structure of protein monomers. Different models of insulin ...fibrillogenesis have been proposed previously. However, precise regions responsible for the formation of amyloid fibrils have not been identified. Using bioinformatics programs for predicting amyloidogenic regions, we have determined some common amyloidogenic sequences in the structure of insulin monomers. The use of limited proteolysis and mass spectrometry analysis of the obtained protein fragments resistant to the action of proteases allowed us to identify amino acid sequences in the insulin structure that can form the spine of the insulin fibrils. The obtained results are in agreement with the earlier proposed model of fibril formation from the ring-like oligomers and can be used for designing insulin analogs resistant to amyloidogenesis.
The results of experimental and theoretical studies of the passage of monochromatic and pulse-modulated microwave signals through the traveling-wave tube operating in the mode of nonlinear ...suppression are presented. It is established that, dependent on the value of the accelerating voltage and beam current, the tube may operate either as a saturable absorber or as power limiter. In the first case, the maximum level of signal suppression corresponding to the Kompfner dip occurs in the linear mode, while it occurs in the nonlinear mode, under a certain power of the input signal, in the second case. It is shown that, in the case of maximum suppression a short pulse is generated at the front of the radio pulses. In the mode of a nonlinear Kompfner dip the duration of such pulse decreases as the power of the input radio pulse increases. The calculation results obtained by the nonlinear transient theory of traveling-wave tube are in good agreement with the experimental results.
Functionally important multidomain bacterial protein bS1 is the largest ribosomal protein of subunit 30S. It interacts with both mRNA and proteins and is prone to aggregation, although this process ...has not been studied in detail. Here, we obtained bacterial strains overproducing ribosomal bS1 protein from
Thermus thermophilus
and its stable fragment bS1(49) and purified these proteins. Using fluorescence spectroscopy, dynamic light scattering, and high-performance liquid chromatography combined with mass spectrometric analysis of products of protein limited proteolysis, we demonstrated that disordered regions at the
N
- and
C
-termini of bS1 can play a key role in the aggregation of this protein. The truncated fragment bS1(49) was less prone to aggregation compared to the full-size bS1. The revealed properties of the studied proteins can be used to obtain protein crystals for elucidating the structure of the bS1 stable fragment.
An electrochemically induced synthesis of imidazoles from vinyl azides and benzyl amines was developed. A wide range of imidazoles were obtained, with yields of 30 to 64%. The discovered ...transformation is a multistep process whose main steps include the generation of electrophilic iodine species, 2
-azirine formation from the vinyl azide, followed by its reactions with benzyl amine and with imine generated from benzyl amine. The cyclization and aromatization of the obtained intermediate lead to the target imidazole. The synthesis proceeds under constant current conditions in an undivided cell. Despite possible cathodic reduction of various unsaturated intermediates with C=N bonds, the efficient electrochemically induced synthesis of imidazoles was carried out.
The presented experimental results demonstrate that microwave pulses of giant amplitude are generated in a klystron generator operating in the self-excited mode of chaotic oscillations. The ...auto-oscillator is assembled using a noisetron scheme that contains two five-cavity floating-drift klystrons serially connected in a ring, one of which operates in the mode of linear signal amplification (the linear klystron) and the other works in the mode of nonlinear signal amplification (the nonlinear klystron). It is established that, at a certain value of the beam current of a nonlinear klystron, intermittency of chaos–chaos type is realized in the auto-oscillation system in the form of chaotic sequences of microwave pulses of giant amplitude formed over the chaotic amplitude background. This type of intermittency is caused by the amplitude bistability of the nonlinear floating-drift klystron.
The spectrum of slow electromagnetic waves (EMWs) existing in a left-handed medium based on a magnetoactive plasma metamaterial has been theoretically studied. The metamaterial under study is a strip ...waveguide completely filled with longitudinally magnetized cold electron plasma containing a periodic structure made from ideally conducting split-ring resonators. It is shown that there exists either one (ordinary) or two (ordinary and extraordinary) slow EMWs in a left-handed medium based on anisotropic plasma, depending on the chosen values of the split-ring resonator eigenfrequency and magnetic induction. It is found that the extraordinary EMW has a negative dispersion, while the dispersion characteristic of the ordinary EMW contains portions of both negative and positive dispersion.
Using Brillouin light scattering microscopy and micromagnetic simulations, we study the propagation and transformation of magnetostatic spin waves across uniformly biased curved magnonic waveguides. ...Our results demonstrate that the spin wave transmission through the bend can be enhanced or weakened by modifying the distribution of the inhomogeneous internal magnetic field spanning the structure. Our results open up the possibility of optimally molding the flow of spin waves across networks of magnonic waveguides, thereby representing a step forward in the design and construction of the more complex magnonic circuitry.
