Lipase is an industrial enzyme, the catalytic efficiency of which is restricted by various environmental factors. To improve this efficiency, immobilization technology has been utilized in the past to improve the stability of lipase in harsh conditions. Immobilization technology can be divided into physical methods and chemical methods. Some unsolved problems remain in current immobilization technology. The interaction between enzyme and immobilization support is weak and reversible during physical adsorption, resulting in poor stability of the immobilized enzyme and the contamination of substrate solution by leached enzymes. In chemical methods, enzyme-active sites might be inactivated due to the chemical reactions between enzyme molecules and support, resulting in a decrease in the enzymes’ catalytic activity (Liu et al., 2018a). The objective of the current study was to construct a nanostructured lipase via Mg-amino-clay as a carrier and improve the catalytic activity and stability of lipase by immobilization. Lipase produced by Aspergillus oryzae was immobilized on aminopropyl functionalized magnesium phyllosilicate (a 2:1 trioctahedral talc-like silicate Mg-amino-clay) via a 1-(3-Dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride (EDC) coupling agent. The physical and chemical properties of the Mg-amino-clay and Mg-amino-clay-based nanostructured biocatalyst (Mg-clay-lipase) were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Optimal immobilization conditions were determined by taking into account the following variables: amount of initial lipase, EDC concentration, and reaction time. The results revealed that the optimum temperature, pH, and thermal stability of Mg-clay-lipase were greater than equivalent values for free lipase under optimal conditions (described below – Process for Immobilization of Lipase on Mg-amino-clay). The Michaelis-Menten constant (Km) values were 5.25 mM and 7.42 mM while the maximum reaction rates (vmax) were 30.58 mM/(L·min) and 55.87 mM/(L·min) for free lipase and Mg-clay-lipase, respectively. The present study provided a new nanostructured biocatalyst and demonstrated that the enzyme activity and stability of Mg-clay-lipase were superior to those of free lipase due to the mechanism of 'interface activation'.

Sarnak’s density conjecture is an explicit bound on the multiplicities of nontempered representations in a sequence of cocompact congruence arithmetic lattices in a semisimple Lie group, which is motivated by the work of Sarnak and Xue ([58]). The goal of this work is to discuss similar hypotheses, their interrelation and their applications. We mainly focus on two properties – the spectral spherical density hypothesis and the geometric Weak injective radius property. Our results are strongest in the p-adic case, where we show that the two properties are equivalent, and both imply Sarnak’s general density hypothesis. One possible application is that either the spherical density hypothesis or the Weak injective radius property imply Sarnak’s optimal lifting property ([57]). Conjecturally, all those properties should hold in great generality. We hope that this work will motivate their proofs in new cases.

The Moscow Syneclise on the East European Platform is an important area for the study of the continental biota of late Permian to Early Triassic age in continuous sections. This study attempts a taxonomic description of the late Permian conchostracan fauna of this area. The rich, new material was collected, bed by bed, during geological and paleontological excavations of lacustrine and fluvial deposits of the Obnora Formation and Vokhma Formation of the late Permian Zhukovian Regional Stage near the towns of Vyazniki and Gorokhovets. The conchostracan fauna of the Zhukovian Regional Stage consists predominantly of Pseudestheria and less frequently of Palaeolimnadiopsis. In the earliest Triassic Vokhmian Regional Stage, a more diverse fauna including Euestheria, Magniestheria, Cornia, Palaeolimnadiopsis, and Rossolimnadiopsis was already recorded. The preliminary taxonomic determination of the pseudestheriids from the Zhukovian Regional Stage is intended to serve as a prerequisite for future studies of late Permian conchostracan biostratigraphy on the regional to interregional scale.

This paper reports the measurement of the energy loss of protons at the energy of 100 keV penetrating a partially ionized hydrogen plasma. The plasma of ne ≈ 1015–16 cm−3; Te ≈ 1–2 eV and lifetime of about 8 µs is created by the hydrogen gas discharge. The experimental results show an increase of a factor of 2.8 in the energy loss, which are in good agreement with the Bethe, Standard Stopping Model, Li–Petrasso and Vlasov models’ predictions within the error limit. The Bethe–Bloch Coulomb logarithm term is found to increase by a factor of 4.0 for free electrons as compared with the situation where bound electrons prevail. The potential application of protons energy loss for diagnosing the electron density in plasma is proposed too.

Experimental and theoretical investigations have made it possible to define more exactly some features of ice formation on solid surfaces

In this study, the formation solid solutions of titanium dioxide- zirconium dioxide (TiO2-ZrO2) system with the supercritical fluid method is described. The particles of solid solutions in the TiO2-ZrO2 system are spherical and form agglomerates, they are amorphous and have a size from 90 to 850 nm. The X-ray patterns of samples calcined above the temperatures of crystallization (450 °C) and phase transition (750 °C) demonstrate the decomposition of the solid solutions above the crystallization temperature and formation of phases in accordance with phase ratios in the TiO2-ZrO2 system at these temperatures. The formation solid solutions of the starting materials are observed in all region of concentrations.

The investigation of spatial and temporal variability of the snow cover in northern Eurasia (snow depth, density, thermal characteristics, water equivalent) includes large-scale fieldwork, modelling and analysis of meteorological data of two winters (2004/05 and 2005/06) from 38 weather stations situated in different climatic conditions and physico-geographical zones. Common regularities and features of snow-cover variability are revealed for these winters, despite their contrasting temperature and precipitation regimes and differences from an average winter, as the time of appearance, duration and depth of snow cover, the number of snowfalls and date of melting. The modelling of snow-cover stratigraphy is based on viscous compression and recrystallization laws. Meteorological information (temperature, wind velocity and precipitation) is used as input for the model. The output is the specific snow-cover stratigraphy according to positioning in different physical–geographical regions and due to the possible variation as determined by winter temperature and precipitation regimes. The peculiarity of snow-cover stratigraphy at the regional scale depends on the meteorological conditions of its formation as well as on the character of landscapes. A satisfactory correlation of the modelled typical columns of the snow cover formed in 2004/05 and 2005/06 in different regions of Russia and of real columns is revealed.

The paper discusses the verification of a previously developed structural dry-snow model based on the regular packing of isometric grains connected by rigid bonds. Using this model, we consider the probable snow-compaction mechanisms at different snow-density ranges (from new to dense snow), limited by critical densities corresponding to the real values of the structural indices of the model: texture looseness, bond rigidity and coordination number. We also obtain the analytic expression for longitudinal wive velocity and for bulk compressibility of snow as functions of density and structural indices. The calculation enables us for the first time to show the whole range of possible values of these important characteristics and to deduce the most probable configuration of the ice matrix in snow of various densities corresponding to the experimental data available on the snow-texture peculiarities and elastic-wave velocities. The model can be used to comprehend the changes in snow mechanical properties during compaction, as well as the steps by which it proceeds.

The various mechanical properties of dry coherent snow are determined by the same structural peculiarities of this medium, that can be described using the model of regular packed grains connected by rigid bonds. Analytic expressions for the many important snow mechanical parameters density elastic moduli, stress wave velocities, strength, etc.) are derived using the model by introducing three non-dimensional principal structural factors: texture friability, bond rigidity and coordination number. Analytic expressions that relate tensile strength to P and S stress wave velocities are proposed and used to examine the interrelations between the internal structure and tensile strength for snow-ice formations in a wide density range. The theoretically derived results and available experimental data are well correlated and form the basis for the development of non-destructive testing methods to evaluate the strength characteristics of snow, using seismic and acoustic measurements.

This paper presents a model of snow structure (model of regular grain packing) that is based on experimental determination of various geometrical characteristics of fine-, medium- and large-grained granular snow. Data analysis supports the possibility of approximating the ice-matrix configuration as a regular lattice of nearly spherical ice grains connected by rigid ice bonds. The model was successfully used for relating microstructural parameters of snow to snow density, compaction behavior and evolution of mechanical properties.

We present results from cold-laboratory observations of changes in isotopic (δ18O and δD) content by sublimation in snow and ice samples under nearly isothermal conditions. The results show large increases in observed δ18O and δD in snow samples within several centimeters of the surface. They contradict the assumption of a non-changing isotopic content due to layer-by-layer transport mechanisms driven by sublimation/desublimation processes. The data also do not support the idea that isotopic changes of snow and firn are limited by the possibility that the ice matrix incorporates the atmospheric water vapor and that forced water-vapor diffusion in the pore space (wind pumping) is a requirement for isotopic content change. The observations show that sublimation from ice samples results in much lower increases in heavy-isotope content in the first several millimetres near the sublimating surface over the same time period, despite sublimation intensities similar to those of the snow samples. The results suggest that continuous phase transitions inside snow (recrystallization) are the process responsible for the isotopic content change because they are the primary mass-exchange mechanism between the snow mass and the surrounding environment. Modeling the isotopic content of the ice matrix therefore requires inclusion of a two-stage process: fractionation at the ice-matrix surface due to repetitive phase transitions, and fractionation due to preferable diffusion of light water isotopes in the pore space. For interpretation of the observed natural isotopic profiles in snow, the first process can be linked to the time a snow layer undergoes recrystallization, while the second process is related to the total ice/snow mass gain/loss determined by the external environmental conditions.

The regular packing of spheres or polyhedrons of various shapes linked by rigid bonds is presented and discussed as a model of snow structure. Basic structural parameters of this model are: the coordination number and introduced dimensionless factors of friability and rigidity. The snow densification is described as successive changes of these parameters. Use of the model allows us to relate the density increase from ~130 to ~320, ~550, ~700, ~820 and 917 kg m−3, while the coordination number of the structure increases accordingly from 3 (friable hexagonal) to 4 (tetrahedral), 6 (cubic), 8, 10, 12 (dense hexagonal). These structural changes are in good agreement with the critical densities established in experimental studies of snow densification and the physical properties of snow. It is shown that the model presented allows us to estimate the mechanical properties of ice-porous media: Young’s modulus, Poisson’s ratio and strength.

The theory of the aerofoil has now been studied to such an extent that, from this province, it is hardly possible to expect further material improvement in its aerodynamical qualities : profiles differing but little from an inverse of a parabola (Joukovski profile) would appear to be the theoretical ideal. Subsequent important progress in that respect may be sought only in another direction, viz., in the application of a series of supplementary contrivances having a marked influence on the properties of the flow around the aerofoil. Here we are referring to such devices as the sucking away of the boundary layer (Absaugeflügel), or the insertion of appliances on the aerofoil itself. Nevertheless, up to the present, only one of the very earliest attempts in this direction, namely, the slotted wing, has developed sufficiently to be in any way widely adopted in contemporary aircraft construction.

In this work, we review current trends in China to investigate beam plasma interaction phenomena. Recent progresses in China on low energy heavy ions and plasma interaction, ion beam-plasma interactions under the influences of magnetic fields, high energy heavy ion radiography through marginal range method, energy deposition of highly charged ions on surfaces and Raman spectroscopy of surfaces after irradiation of highly charged ions are presented.

The aim of our study was to distinguish the stress-related molecular response of thepulmonate mollusc Lymnaea stagnalis from the Chernobyl area in comparisonwith the consequences of other harmful effects, including the short-term effects ofradiation and heating. Specimens inhabiting ponds near the Chernobyl nuclear power plant,the cooling channel of the electric power station and the soil-reclamation channel (groupsR, T and C, correspondingly), and specimens adapted to laboratory conditions (a controlgroup (CL), a disposable group exposed to 2 mGy X-ray radiation over the body (RL), and agroup exposed to 25 °C for 4 days (TL)) were compared. Despite high variability ofresponses, Principle Component Analysis distinctly separated the laboratory and feralgroups into two sets. In the feral groups, low levels of the stress-related andmetal-binding protein metallothionein (MT), protein carbonyls and lactate dehydrogenase inthe digestive gland were indicated. The main separating criteria selected byclassification and regression tree analysis were the protein carbonyls, cholinesterase andMT. Molluscs from group R were clearly distinguished by the lowest levels of MT,Mn-superoxide dismutase and lactate dehydrogenase, and the highest level of glutathione,demonstrating that the oppression of the gene-determined stress-related response and itspartially metabolic compensation can be possible markers for chronic environmental effectsof irradiation.

In 1986–2009 the dynamics of the radionuclide contamination of the Pripyat inlet ánd Perstok Lake and their biota as well as the set of biological test criteria reflecting impact of ionizing radiation on pulmonate mollusk Lymnaea stagnalis from these reservoirs have been investigated. The γ-activity of biota after the highest level in 1987 (up to 1100 kBq kg−1 wet mass) quickly decreasing. In 2005–2008 the activities of biota in the Pripyat inlet dropped to the natural level, but in the Perstok Lake they remained a rather high – up to 4000 Bq kg−1. Alongside the increase of activity of transuranium α-isotope 241Ám in bottom sediments of the Perstok Lake has been observed since 2006. In the L. stagnalis population in the Perstok Lake the obvious negative effect of chronic impact of radiation was noted. The share of cells with the micronuclei has considerably grown there if compared with the mollusks from the Pripyat inlet. The negative effects mentioned above did not influenced seriously on the viability on organism and populations levels. So, the embryonic mortality in both populations is low and they are capable to maintain sufficient level of reproduction despite the chronic radioactive impact.