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The current study for the period (March 2019 - February 2020) was carried out on three different land-based ecosystems in three Iraqi governorates (Sulaymaniyah, Kirkuk, and Anbar). Soil samples were collected at nine stations close to pollution sources (Bazian cement plant, North Oil concentration area). , Haditha Desert) is located between longitude and latitude (45.062554 _ 35.577087) (44.217077 _ 34.406426) (42.269622 _ 34.8764) respectively. The relative humidity values ranged from (0.20%–39.57%) (the third station (desert) - the second station, cultivated land), while the results of bacterial numbers were recorded (75 × 310–295.66 × 510) cfu. G1-dry soil at (the third station, desert) Haditha and at the first station - Al-Wadi). 16 bacterial isolates were isolated from Acinetobacter haemolyticus. Removal was carried out under conditions of 37 °C and pH = 7, with a 24-hour incubation time. Varying concentrations of heavy elements were recorded after biological treatment with Acinetobacter haemolyticus using low concentrations (0.5, 1, 2) mg / L. The elements, cadmium (Cd), and lead (Pb) were removed. Zn, Zn, and Ni, and it was found that the total removal of lead Pb and Ni is 100% from the concentrations of low elements individually and in combination with varying values of the other elements, while there is a relative difference for the concentrations of heavy elements at high concentrations.

Fluoride is a natural contaminant of water – that endangers many people worldwide when present in concentrations higher than 2 ppm. Here, fluoride removal by four different nanostructured colloidal particles (SiO2@ZrO2nc, SiO2@ZrO2c, @ZrO2nc, and @ZrO2c) was measured in batch systems within a period of 24 h. Surprisingly, these materials removed fluoride from the water solutions and reached equilibrium in less than 10 min. The combination of high specific surface and fast fluoride removal placed these materials among the top materials currently known in fluoride removal. Also, the impact of element leaching was measured and quantified. The influence of time, pH, and fluoride concentration on leaching of Zr and Si was evaluated with a response surface methodology. Leaching of Zr and Si continued for several hours and depended on first-order, quadratic and cross-product coefficients. Previous studies of fluoride removal with zirconium oxide often assumed that a decrease in fluoride concentration in the solution indicated that fluoride was bound to the surface of the oxide. Zirconium oxide's solubility in water is low, but not zero. Hence, Zr might have formed soluble fluorocomplexes. This is the first report of fluoride removal with zirconium oxide that studied the leaching of the solid to exclude the formation of soluble fluorocomplexes.

Periodic Nonuniform Samplings of order N (PNSN) are interleavings of periodic samplings. For a base period T, simple algorithms can be used to reconstruct functions of spectrum included in an union of N intervals δk of length 1/T. In this paper we study the behavior of these algorithms when applied to any function. We prove that they result in N (or less) foldings on , each of δk holding at most one folding.

We propose Reduced Collatz Conjecture that is equivalent to CollatzConjecture but is easier to explore, because reduced dynamics ismore primitive than original dynamics and presents better structures(e.g., period and ratio). Reduced dynamics (that are occurredcomputation sequence from a starting integer to the first integerless than the starting integer) is the component of originaldynamics (from a starting integer to 1). Reduced dynamics of x isrepresented by a sequence of computation that is either (3*x+1)/2 orx/2, because 3*x+1 is always even and followed by x/2. We prove thatreduced dynamics is periodical and its period equals 2 to the powerof the count of x/2. More specifically, if there exists reduceddynamics of x, then there exists reduced dynamics of x+P, where Pequals $2^L$ and L is the total count of x/2 computations in reduceddynamics of x (equivalently, L is the length of the sequence).

The results of the analysis on some fragments of bronze belts and a bowl discovered from southwestern Armenia, Yegheghnadzor archaeological site, are discussed. The samples are dated to the 7-6 BCE from the Urartian period. The artifacts were corroded and a multilayer structure was formed. To study the stratigraphy of layers and their composition the samples have been analyzed using SEM-EDS (Scanning Electron Microscopy, Energy Dispersive Spectrometry) and OM (Optical Microscopy) techniques. The bronze finds appear with the typical incrustations rich in alloy alteration compounds. Concentrations of copper and tin in the alloys were quantified by SEM-EDS: the pattern and the percentage of the alloy are the same for the belts. Regarding the bowl sample, it is constituted by two foils, perfectly in contact but different in colour, thickness and composition. The results evidenced that only two elements participate in forming alloy composition in the samples: Cu and Sn. The tin content is variable from 7.75 to 13.56%. Other elements such as Ag, As, Fe, Ni, P, Pb, Sb, and Zn are lower more than 1% and can be considered as impurities. This article is protected by copyright. All rights reserved.

The simplest frequency formulation for conservative oscillators was proposed in 2019 (Results Phys 2019;15:102546). However, it becomes invalid for non-conservative oscillators. This work suggests the simplest amplitude-period formulation for non-conservative oscillators. The existence of a periodic solution of a second-order ordinary differential equation is given, and the periodic orbits are easily obtained. To the best of the authors’ knowledge, such a powerful result is not available in the literature, providing a tool to determining periodic orbits/limit cycles in the most general scenario.

A bifurcation tree of period-3 motions to chaos in an inverted pendulum with a periodic base movement is presented through a discrete implicit mapping method. The stable and unstable periodic motions on the bifurcation tree are achieved semi-analytically, and the corresponding stability and bifurcation of the periodic motions are also carried out. Frequency-amplitude characteristics of the bifurcation tree are presented through the finite Fourier series analysis. Numerical simulations of periodic motions on the bifurcation are completed. The numerical and analytical results are presented for comparison. Except for period-1 motion to chaos studied before, this study focuses on other periodic motions to chaos existing in the inverted pendulum with periodic base movement. In the earthquake testing, one tests structures from 1hz to 33 hz. However, during such a frequency range, one not only can observe the period-1 motion to chaos, but one can observe period-3 motion to chaos in such an inverted pendulum with a periodic base movement. Thus, in the building design, period-3 motions to chaos should be considered, which have different dynamical behaviors from the period-1 motions to chaos.

Studies have been carried out when grinding alloys based on titanium, vanadium, chromium, iron, cobalt and nickel. According to the condition of the neat surface, the alloys are divided into groups. The regularities of changes in the roughness parameters of Ra and Rsm are investigated. The parameter of the average density of the peaks of the grains forming the elements of the surface roughness profile has been introduced, the relationship of the introduced parameter with Ra is shown. It is established that when grinding all alloys, the treated surface is impregnated by the wear products of the abrasive tool. Electronic photographs of objects are given. The possible sizes of embedded crystals are determined.

Soil samples were collected at a depth of 0-30cm within two steel markets and a control site in Port Harcourt, Rivers State Nigeria to assess the level of heavy metals (Fe, Pb, Cu, Cd, Cr, Ni and As) in the environment. Atomic Adsorption Spectrophotometer was used to analyze the samples for heavy metals. The concentrations of all the heavy metals in the steel rods markets exceeded that of the control. The results indicated that heavy metals concentrations in the sites were in the order; Mile III > Kala > RSU. The average levels of contamination of heavy metals recorded followed the order Fe > Cr > Cu > Pb > Ni > As > Cd in Mile III, Fe > Pb > Cu > Cr > Ni > As > Cd in Kala and Fe > Cu > Pb > Cr > Ni > As > Cd in RSU (control). Mean concentrations obtained for heavy metals within the months of investigation were; 1420.931±9.155, 7.753±0.184, 8.730±0.050, 2.843±0.124, 9.428±0.122, 7.433±0.047 and 3.732±0.047 mg/Kg for Fe, Pb, Cu, Cd, Cr, Ni and As respectively at the mile III station, while the mean concentrations of heavy metals observed at the Kala station were; 1161.173±1.823, 9.425±0.054, 7.596±0.027, 1.425±0.020, 6.507±0.006, 5.455±0.033 and 1.901±0.010 mg/Kg for Fe, Pb, Cu, Cd, Cr, Ni and As respectively. The mean values of heavy metals concentrations observed at the RSU station within the period were; 892.064±1.025,5.603±0.007, 5.841±0.051, 0.173±0.005, 3.389±0.009, 2.309±0.010 and 0.706±0.006 mg/Kg for Fe, Pb, Cu, Cd, Cr, Ni and As respectively. Pollution assessment models used for assessing the anthropogenic input on the quality of the soil in the area using the control site as the basis of judgment were: contamination factor (CF), pollution load index (PLI), contamination degree (CD), modified contamination degree (mCD), potential ecological risk coefficient (Eir), potential ecological risk index (RI), Geo-accumulation index (Igeo) and anthropogenicity. These indices revealed that the steel markets were contaminated and polluted and poses ecological risks by heavy metals, even though the values obtained were still below the WHO acceptable limits. The steel rods markets need to be adequately monitored and regulated to avoid further soil contamination by heavy metals to a degree that will be dangerous to human health.

(R, S)-2-Chloromandelic acid, which can crystallize in racemic crystals (forms α and β) or a conglomerate (form γ), has been studied for its glass-forming behavior. Below the glass transition temperature, samples of the title compound crack into pieces. Correlation plots of DSC results have been used to investigate what determines the cracking and its occurrence temperature. We found that the latter is influenced by the polymorph from which the melt state has been obtained, showing that a certain memory of the previous crystalline phase persists in the undercooled melt. Moreover, this residual structure could be eliminated by elongating the annealing period or increasing the annealing temperature. Investigation using broadband dielectric spectroscopy confirmed such a memory effect. Finally, we studied the role of cracking in the control of the crystallization. In contrast with previous literature on other glass-forming molecular systems, we verified that the crystallization upon reheating is not impacted by the occurrence of cracks in the glassy state. This observation challenges the current views on polymorphic crystallization from organic glasses.

The undesirable loss of methane (CH4 ) at remote locations welcomes approaches that ambiently functionalize CH4 on-site without intense infrastructure investment. Recently, we found that electrochemical oxidation of vanadium(V)-oxo with bisulfate ligand leads to CH4 activation at ambient conditions. The key question is whether such an observation is a one-off coincidence or a general strategy for electrocatalyst design. Here, a general scheme of electrocatalytic CH4 activation with d0 early transition metals is established. The pre-catalysts' molecular structure, electrocatalytic kinetics, and mechanism were detailed for titanium (IV), vanadium (V), and chromium (VI) species as model systems. After a turnover-limiting one-electron electrochemical oxidation, the yielded ligand-centered cation radicals activate CH4 with low activation energy and high selectivity. The reactivities are universal among early transition metals from Period 4 to 6, and the reactivities trend for different early transition metals correlate with their d orbital energies across periodic table. Our results offer new chemical insights towards developing advanced ambient electrocatalysts of natural gas.

The objects of consideration are thin linearly thermoelastic Kirchhoff-Love-type circular cylindrical shells having a periodically microheterogeneous structure in circumferential and axial directions (biperiodic shells). The aim of this contribution is to formulate and discuss two new averaged mathematical models for the analysis of selected dynamic thermoelasticity problems for the shells under consideration: the non-asymptotictolerance and the consistent asymptotic models. The starting equations are the well-known governing equations of linear Kirchhoff-Love theory of thin elastic cylindrical shells combined with Duhamel–Neumann thermoelastic constitutive relations and coupled with the known linearized Fourier heat conduction equation in which the heat sources are neglected. For the microperiodic shells under consideration, the starting equations mentioned above have highly oscillating, non-continuous and periodic coefficients. The tolerance model is derived applying the tolerance averaging technique and a certain extension of the known stationary action principle. It has constant coefficients depending also on a cell size. Hence, this model makes it possible to study the effect of a microstructure size on the global shell thermoelasticity (the length-scale effect). The consistent asymptotic model is obtained using the consistent asymptotic approach. It has constant coefficients being independent of the period lengths. Moreover, the comparison between the tolerance model for biperiodic shells proposed here and the known tolerance model for cylindrical shells with a periodic structure in the circumferential direction only (uniperiodic shells) is presented.

Fe doped La2CoMnO6 perovskite La2Co(1-x)FexMnO6 (abbreviated as LCFxMO, x = 0.1˜0.4) ceramics exhibiting P21/n phase and dense structure with micron grains resulted from the lower sintering temperature of 930 °C were fabricated by plasma activated sintering. The Co2+/Mn4+ concentration in LCFxMO ceramics gradually increased with the increase of Fe doping, then decreased due to excessive doping, reflecting the change of order degree of B-site cations. The Co2+/Mn4+ concentration reached the highest value in LCF0.2MO, which proved the ascendant B-site cations ordering degree of LCF0.2MO. Moreover, the smaller grains resulted from rapid sintering period was also one of another cause of high order degree. It was found that the saturation magnetization was greatly enhanced by a small amount of Fe doping. Comparing to other Fe doped content of LCFxMO ceramics, the LCF0.2MO ceramic also had the largest saturation magnetization (57.05 emu/g).

Our work is concerned with the bifurcation of critical period for a quartic Kolmogorov system. By computing the periodic constants carefully, we show that point (1,1) can be a weak center of fourth order, and the weak centers condition is given. Moreover, point (1,1) can bifurcate 4 critical periods under a certain condition. In terms of multiple bifurcation of critical periodic problem for Kolmogorov model, studied results are less seen, our work is good and interesting.

Objective: To compare the characteristics of hydraulic potential in worn steel pipes with internal deposits subjected to cleaning by mechanical and chemical methods. Methods: Calculated dependencies are used for hydraulic calculation of new metal pipes and pipes with internal deposits. Results: A calculated dependence was obtained to determine the value of the inner diameter of pipes with any thickness of the layer of internal deposits. The concept of an efficient pipeline is introduced and a comparison made of the values of head losses in new pipes and in pipes with internal deposits. A specific practical example is considered. For the given example, compare the values of energy consumption of pumping equipment for two methods of cleaning the inner surface of pipes. Measures are indicated to ensure the efficiency of operation of water supply networks. Practical importance: It is shown that the chemical method of technical regulation of the hydraulic characteristics of new steel pipes provides an extension of the period of their further use.

The topic of this article lies in the field of problems: substantiating the periodic system of isotopes and the principle of multilevel periodicity using quantum mechanical calculations, combining strong and electromagnetic interactions, and searching for the fundamental cause of periodicity in general. This article is a theoretical section and a continuation of the article: "Periodic system of isotopes", in which the system was checked against 10 types of experimental data, the periodic change of properties at the level of nuclei and the vertical symmetry of subgroups of isotopes were found. Periodic system of isotopes was constructed with the help of a special algorithm, the principle of multilevel periodicity of the atom, from the electrons to the nucleus. As a description of the multilevel periodicity, this paper presents a unified system of quantum numbers, which is used to describe both electron and nucleon shells (binomial probabilistic interpretation). With the binomial interpretation the problem of a particle in a one-dimensional potential well has been solved; quantummechanical calculations for the probability functions of the orbitals and periods of both electrons and nucleons have been performed - characteristic equations have been obtained, the projections of electronic orbitals have been reproduced and the binomial interpretation has been shown to correspond to the family of spherical harmonics. For the electron orbitals the calculation and analysis of solutions of the Schrödinger equation for the binomial interpretation of quantum numbers have been performed. The spatial nature of quantum numbers, for this interpretation, in the form of degrees of freedom is shown. Based on the principle of multilevel periodicity, expressions are derived and planar projections of nucleon nucleon orbitals are constructed, and similarity of the forms with electron orbitals is analyzed and revealed. A critical analysis of the modern spherical coordinate system was made, possible errors in the construction of electron orbitals were shown and, taking into account the drawbacks, two alternative spherical coordinate systems were proposed, for which Lame coefficients were calculated and Laplace equations were derived. As a search for the fundamental cause of multilevel periodicity, a spatial model with changing degrees of freedom 0-n is presented, its manifestation in nature (crystal forms) is found; a number of experiments are proposed; the predictions about the applicability of the multilevel periodicity principle in quark theory are made

This article presents a nonlinear site amplification model for ground-motion prediction equations (GMPEs), using site period as site-effect proxy based on the measured shear-wave velocity profiles of selected KiK-net and K-NET sites in Japan. This model was derived using 1D equivalent-linear site-response analysis for a total of 516 measured soil-site shear-wave velocity profiles subjected to a total of 912 components of rock-site records. The modulus reduction and damping curves for each soil layer were assigned based on the soil-type description for a particular layer. The site period and site impedance ratio affect both the linear and nonlinear parts of this study, and were used as the site parameters in the 1D amplification model. A large impedance ratio enhances the amplification ratios when the site responds elastically and enhances the nonlinear response when the site develops a significant nonlinear response. The effects of moment magnitude and source distance on the linear part of the 1D amplification model were also incorporated in the model. To implement the 1D amplification model into GMPEs, a model adjustment is required to match the GMPE amplification ratio at weak motion and to retain the nonlinear amplification ratio at the strong motion of the 1D model. The two-step adjustment method by Zhao, Hu, et al. (2015) was adopted in this study with significant modifications. It is not possible to obtain a credible second-step adjustment parameter using the GMPEs dataset only. We proposed three methods for calculating the scale factors. Method 1 is a constant angle in a 30°–60° range for all spectral periods; method 2 was based on the GMPE dataset and 1-D model parameters; and method 3 was based on the strong-motion records used for the 1D site modeling. A simple second-step adjustment factor leads to smoothing amplification ratios and soil-site spectrum.

We study one-dimensional cellular automata evolutions with both temporal and spatial periodicity. The main objective is to investigate the longest temporal periods among all two-neighbor rules, with a fixed spatial period $\sigma$ and number of states $n$. When $\sigma = 2, 3, 4$, or $6$, and we restrict the rules to be additive, the longest period can be expressed as the exponent of the multiplicative group of an appropriate ring. We also construct non-additive rules with temporal period on the same order as the trivial upper bound $n^\sigma$. Experimental results, open problems, and possible extensions of our results are also discussed.

This review is the first in a series that deals exclusively with electrophoresis of ions. Since in modern terminology "electrophoresis is the movement of dispersed particles relative to a fluid under the influence of a spatially uniform electric field”, electrophoresis is not limited to colloidal particles, it includes ions as well. The history of electrophoresis of ions therefore begins in 1800 at the same time as that of electrolysis, because the two phenomena are so inextricably linked “that one cannot happen without the other” (Faraday, 1834). Between 1800 and 1805 about half a dozen different theories of electrolytic decomposition and the movement of the particles - for which we coin the term electrophoretic current - were formulated, all contributing to the discourse, but lacking consistency and none fully convincing. They are discussed nonetheless because most of them fell into oblivion, even though they are interesting for historical reasons. However, from 1805/1806 the predominant theory, formulated by Theodor von Grotthuß and independently by Humphry Davy assumed that polarized molecules of water or dissolved ions form chains between the two electrodes. Only the terminal atoms of these chains were in direct contact with the electrodes and were liberated by galvanic action, but are immediately replaced by neighboring atoms of the same type. This decomposition and recombination of the molecules driven by electric forces which follow the “action at a distance” principle like in Coulomb´s law takes place over the entire chains; they represent the electrophoretic current. However, in 1833 Michael Faraday refuted all previous theories. Two of his groundbreaking findings were of particular importance for the electrophoresis of ions: one was that electricity consists of elementary units of charge. The ions thus carry one or a multiple of these units. The other was the revolutionary theory of the electric lines of force in early 1840s, and of what was later called the electric field. With these findings Faraday fundamentally changed the previously prevailing view of the electrophoresis of ions.

Sustainable life on Earth could not exist without breathable air or molecular oxygen, which makes up 21% of the atmosphere we breathe today. Oxygen did not always exist in the atmosphere, and it is believed that it evolved in a period in Earth's history around 2.33 billion years ago, known as the Great Oxygenation Event (GOE). Prior to this time, in the first 2 billion years since Earth was formed, oxygen was not present in the atmosphere. Earth's atmosphere was initially extremely hot, composed of about 75% hydrogen and 25% helium, which was identical to the atmosphere of most stars [1], [2]. In fact, hydrogen is the most common element in the universe today, composed of 90% of all matter, but being the lightest in weight of all gases, when the Earth cooled, it almost completely drifted off into space.

We theoretically study periodic oscillation and its period of a circadian rhythm model of Neurospora and provide the conditions for the existence of such a periodic oscillation by the theory of competitive dynamical systems. To present the exact expression of the unique equilibrium in terms of parameters of system, we divide them into eleven classes for the Hill coefficient $$n=1$$ or $$n=2$$ , among seven classes of which nontrivial periodic oscillations exist. Numerical simulations are made among the seven classes and the models with the Hill coefficient $$n=3$$ or $$n=4$$ to reveal the influence of parameter variation on periodic oscillations and their periods. The results show that their periods of the periodic oscillations are approximately 21.5 h, which coincides with the known experiment result observed in constant darkness.

For any group $G$ and any set $A$, consider the shift action of $G$ on the full shift $A^G$. A configuration $x \in A^G$ has \emph{least period} $H \leq G$ if the stabiliser of $x$ is precisely $H$. Among other things, the number of such configurations is interesting as it provides an upper bound for the size of the corresponding $\text{Aut}(A^G)$-orbit. In this paper we show that if $G$ is finitely generated and $H$ is of finite index, then the number of configurations in $A^G$ with least period $H$ may be computed using the M\"obius function of the lattice of subgroups of finite index in $G$. Moreover, when $H$ is a normal subgroup, we classify all situations such that the number of $G$-orbits with least period $H$ is at most $10$., Comment: 8 pages

An estimate of the labile fractions of different trace metals (Mn and Pb) in soil from two dumpsites with complexing agents (EDTA and Citrate) was carried out. The dump sites used for this study receives both commercial and domestic wastes. Physiochemical parameters and the total metal concentrations of the soil was determined, extraction with EDTA and Citrate were used to study the potential metal extraction capacity at different time intervals and the extraction rates of metal released as a function of time (between 0 to 24 hr). The relatively low levels of silt, clay, organic matter and CEC indicates high permeability, hence leachability of heavy metals in the soil and suggest that it might be amenable to remediation by soil washing. The removal efficiency showed that complete solubilization of metals did not occur, as not all the complexing agents added to the soil, was bound to the target metal. This might be due to the presence of other ions such as Ca and Fe which form relatively high stable complexes. EDTA yielded much more than citrate for both metals under consideration. Lead was extracted more than Manganese, which suggest Lead has been more labile in solution than Manganese and EDTA as a stronger complexing agent than citrate. The level of extraction was constant for the period of 60 min to 720 min after which it increased considerably

A large-scale experiment on coal spontaneous combustion (CSC) was conducted to investigate the experimental spontaneous combustion period (ESCP) and limit parameters. Coal samples were collected fr...

We report the discovery of a rare close binary system, SMSS J160639.78-100010.7, comprised of a magnetic white dwarf with a field of about 30 MG and a brown dwarf. We measured an orbital period of 92 min which is consistent with the photometric period. Minimum and maximum light occur at the orbital quadratures Phi=0.25 and 0.75, respectively, and cannot be caused by reflection on the brown dwarf, but, instead, by a spot on the synchronously rotating magnetic white dwarf. The brown dwarf does not fill its Roche lobe and the system may be in a low-accretion state or, more likely, in a detached state following episodes of mass transfer. SMSS J160639.78-100010.7 is the nearest known magnetic white dwarf plus brown dwarf system., Comment: Accepted for publication in MNRAS Letters

Life assessment predictions of reformer tubes of HP40Nb grade steel used in the petrochemical industry were investigated by quantitative metallographic evaluations of the area fractions of precipitated carbides. Correlations were established between the field-service periods and area fractions of the carbides via microstructural analysis. The microstructures of the virgin and other tubes were examined using optical microscopy (OM) for service periods of 1.8, 6.0, 7.2, 8.5, 9.7, and 16.2 years at 950 °C. The area fractions of the precipitates were measured by image analysis using ImageJ software. The results showed that increase in the area fractions of the precipitates was almost proportional to increase their service times. The relationships between area fractions of the precipitates and service times were also discussed for a 6-year cracked tube and a tube that had been in service for 11.5 years at another furnace. The obtained relationship can thus be used via the surface replication method for on-site residual life assessments.

This paper presents a complete analysis and a numerical application for deducing the optimum solar collector size to satisfy the heat requirement per year for certain estimated life-time of the heating system. Total cost of the heating systems (collector and auxiliary one) is computed for various collectors areas. The collectors area corresponding to the minimum total cost yields the optimum collector size. This goal is very significant since with increasing collector size, the solar contribution will be greater but certain heat collected will wasted if there is no simulataneous demand. On other hand, it is unequivocal that a small collector of only a few square meters would be utilized all year round. Various collector cost functions are assumed to establish its influence on both optimum and maximum collector size beyond which the estimated life-time cost would be more than a conventional one.

The results of structural studies of GaN nanowires containing screw dislocations are presented. It is found that the length of the Burgers vector of dislocations may reach 5 nm, i.e., exceed many times the c parameter of the gallium nitride unit cell. The formation of such dislocations leads in some cases to the occurrence of an ordered sequence of basal stacking faults with a period of 1.3–3.9 nm.

An investigation is performed of the patterns of CO2 chemisorption by the carbon dioxide sorbent Drager 800+. The dynamics of changes in textural characteristics, phase, and chemical compositions of the material in the process of chemisorption at the level of individual sorbent granules are studied. The dependence of the period of the protective action of the sorbent on the height of its layer, and on the flow rate and concentration of carbon dioxide in the initial gas–air mixture is determined. Based on experimental data, an empirical equation is obtained that can be used to predict the period of protection by a layer of granules of Drager 800+ absorber at known contact time and concentrations of carbon dioxide in the gas mixture.

Heavy metals pollution has become a more serious environmental problem in the last several decades as a result of releasing toxic materials into the environment. The aim of this study is to develop an ecological method for the removal of Ni2+ ions from industrial wastewater by an electro coagulation method using aluminum plates and solar cell as a source of D.C current. In this study, different conditions of pH of 4, 6, 7, and 8, current densities of 0.5, 1.0, and 1.5 mA/cm2, and nickel ion concentrations of 200, 300, and 500 ppm were investigated during a period of time of 120 minutes to remove nickel ions prepared waste water by electro coagulation. The total removal of nickel ions was (97.5- 99.5%), (97- 99%), and (96.67-98.8%) for pH (4-8), current density (0.5-1.5 mA/cm2) and nickel ions concentration (200-500 ppm), respectively. The results show that the optimum condition of electro coagulation process can be obtained at pH = 8 and current density 1.5 mA/cm2 when 120 minutes were elapsed.

Lithium–lead alloys are of main interest in the liquid state. They were subjects of numerous studies, in particular, of those dealing with structural ordering in the liquid phase. Lithium–lead alloys show promise for use in liquid metal energy conversion systems and in nuclear power engineering. The results of studying thermodynamic properties of liquid Li–Pb alloys by various methods in the period from 1973 to 2018 are summarized and analyzed in the paper. Treatment of the whole set of the experimental data allowed choice of the recommended values of the thermodynamic functions for the composition interval that is of interest for technological purposes (0 ≤ xLi ≤ 0.50, with a step of 0.05). The calculation results are presented in the tabular form and are described by polynomials.

One of the National Research Programs (PRN) in the energy sector of the Indonesian Ministry of Research and Technology for the period of 2020-2024 is small modular reactor (SMR) nuclear power plant (NPP) assessment. The France’s Flexblue is a PWR-based SMR submerged reactor with a power of 160 MWe. The Flexblue reactor module was built on the ocean site and easily provided the supply of reactor modules, in accordance with the conditions of Indonesia as an archipelagic country. Therefore, it is necessary to know the release of fission products (source term), which is necessary for the study of the radiation safety of a nuclear reactor. This paper aims to examine the source term in normal operating conditions and abnormal normal operating conditions, as well as postulated accidents. Based on the Flexblue reactor core parameter data, the calculation of the reactor core inventory uses the ORIGEN2 software is previously evaluated. The source term calculation uses a mechanistic approach and a graded approach. The normal source term is calculated assuming the presence of impurities on the fuel plate, due to fabrication limitations. Meanwhile, the abnormal source term is postulated in the LOCA event. The core reactor inventory and source term is divided into 8 radionuclide groups which are Noble gasses group (Xe, Kr); Halogen (I); Akali Metal (Cs, Rb); Tellurium Group (Te, Sb, Sc); Barium-Strontium Group (Ba, Sr); Noble Metals (Ru, Rh, Pd, Mo, Tc, Co); Lanthanides group (La, Zr, Nd, Eu, Nb, Pm, Pr, Sm, Y, Cm, Am) and Cerium Group (Ce, Pu , Np).

The effectiveness of the use of mixed ligand complexes of Zinc, Manganese and Cobalt in the diets of high-yielding cows in the final period of lactation, and their effect on productivity, nutrients digestibility and nitrogen metabolism in the animals’ body was studied in a scientific economic experiment conducted at the Terezyne Ltd. of Bila Tserkva district, Kyiv region. Five groups of highly productive cows of Holstein, Ukrainian red-spotted and Ukrainian black-spotted dairy breeds were selected on the principle of analogues. The difference in feeding cows of the groups was in the following: - the diet of the control 1st group was balanced to the norm only with trace elements of Selenium, Copper and Iodine. - cows of the 2nd and 3d experimental group were fed with the norm of all trace elements (for the 2nd experimental groupthe norm was provided due to introducing sulfates of Zinc, Manganese, Cobalt, Copper, Selenium Suplex and Potassium iodide; for the 3d experimental group , sulfates of Zinc, Manganese and Cobalt were substituted with their mixed ligand complexes). - for cows of 4th experimental group, the concentration of Zinc, Manganese and Cobalt in 1 kg of dry matter feed was reduced by 11% compared to the group 3. - for the 5thgroup it was 22% lower than in the group 3. The results of the studies show that the use different doses of mixed ligand complexes of Zinc, Manganese, Cobalt in cows feeding with the use of Selenium Suplex, Copper sulfate and Potassium iodide during the final 100 days of lactation did not affect milk productivity. Each cow of the control group in the final period of lactation yielded 2220 kg of natural milk, whereas the cows of the experimental groups 2-5 yielded 40-120 kg more. The difference in the average daily milk yield of 4% fat was 0.5–1.91 kg, and this difference was significant (p

Xiao, Zeng, Li and Helleseth proposed new generalized cyclotomic binary sequences $$s^{\infty }$$ of period $$p^m$$ and showed that these sequences are almost balanced and have very large linear complexity if p is a non-Wieferich prime and $$m=2$$ . Wu, Xu, Chen and Ke determined the values of the k-error linear complexity for $$m=2$$ in terms of the theory of Fermat quotients and the results indicated that sequences $$s^{\infty }$$ have good stability. Edemskiy, Li, Zeng and Helleseth studied the linear complexity of $$s^{\infty }$$ for general integers $$m\ge 2$$ . Furthermore, Ouyang and Xie constructed new $$2p^{m}$$ -periodic binary sequences $${\widehat{s}}^{\infty }$$ and $${\widetilde{s}}^{\infty }$$ and proved that the sequences $${\widehat{s}}^{\infty }$$ and $${\widetilde{s}}^{\infty }$$ are of high linear complexity when $$m\ge 2$$ . In this paper we shall show that despite a high linear complexity the sequences $$s^{\infty }$$ , $${\widehat{s}}^{\infty }$$ and $${\widetilde{s}}^{\infty }$$ have some undesirable features which may not suggest them for cryptography. The properties of multiplicative character sums modulo $$p^m$$ play an important role in the proof of this paper.

Abstract The paper presents a quick method for the quantification of nickel species in spent FFC catalysts; the quantification of known quantities NiO and $$\hbox{NiAl}_2\hbox{O}_{4}$$ NiAl 2 O 4 is first done in a matrix of fresh zeolite Y, and then in a complex matrix, similar to the one of a real spent catalyst. The method is carefully checked and the errors in the quantification are critically evaluated. After the validation of the method with known quantities of NiO, well below the law limit for direct re-use, a set of real spent catalysts (representative of a period of 12 months) is analysed. Graphic Abstract

The concentrations of heavy metals in the form of free elements or oxides, as well as arsenic in samples of atmospheric aerosol and soils, collected in northern Tajikistan in the period from 2011 to 2019, are determined. Local sources of heavy metals, mainly anthropogenic (motor vehicles, metallurgical industrial plants, open tailing dumps, etc.) in origin, are discussed. Possible sources of air transport of pollutants to the territory of the Sogd region are identified on the basis of the HYSPLIT back trajectory model.

Eigenwaves in the structure of coupled EBG waveguides with a sparse lattice of coupling elements, as well as characteristics of directional couplers based on them, are investigated. The propagation constants of even and odd waves in a system of two coupled triple waveguides the common wall of which is a sparse lattice of metal cylinders with a period twice the period of the crystal. It is shown that a 3 dB directional coupler, in which the waveguides are coupled through a sparse grating in a common wall, has a rather weak frequency dependence of the transmission coefficients and the matching is no worse than –20 dB in a frequency band up to 30%.

The results of establishing the optimal feeding doses of Zinc, Manganese, and Cobalt in the form of their mixed-ligand complexes for high-yielding cows of Holstein, Ukrainian Red-Spotted and Ukrainian Black-Spotted dairy breeds during the late dry period were presented, their influence on the future productivity and reproductive qualities of cows were also determined. It was found that lower doses of mixed-ligand complexes of Zinc, Manganese, and Cobalt in the feed mixture stimulated its consumption better. The cows of the 4th experimental group consumed more of the feed mixture, where the concentration of Zinc and Manganese was 35 mg, and Cobalt – 0.49 mg per 1 kg of DM. At various doses of mixed-ligand complexes of Zinc, Manganese, and Cobalt, the increase in live weight in cows of the control group was 24.3 kg, and in the experimental groups, it ranged from 23.7 kg to 26.9 kg, which is 8.6% and 10.7% (P < 0,05) more in the 3rd and 4th groups compared with the control. A decrease in the concentration of mixed-ligand complexes of Zinc, Manganese, and Cobalt in the diets of dry cows in the experimental groups by 10, 20, 30 and 40% had a positive effect on their further milk productivity. During the first 100 days of lactation, they milked 60-180 kg of milk more compared to the control with an increase in fat content by 0.01–0.05%. Also, in the milk of experimental group’s cows, compared with the control, the protein content increased (3.22–3.23% versus 3.14%), and the feed costs per 1 kg of milk in them were lower by 3.5–9.4%. Smaller doses of zinc, manganese, and cobalt contributed better to lengthening the period of prolonged action of their mixed-ligand complexes on the body of lactating cows. The calves’ live weight at the birth in the 4th experimental group exceeded the indicator of their peers from the control group by 2.3 kg or 8.81%, while the calves obtained from cows of the 2nd experimental group prevailed the control by 1.6 kg, or 6, 13 %, from the 3rd experimental group – by 1.8 kg, or 6.90%, and the 4th experimental group – by 1.7 kg, or 6.51%. The duration of the service period in all experimental groups of cows was within the recommended norms and was 87.8 days in the control group, and the 2nd, 3rd, 4th and 5th experimental groups, respectively 84.7 days, 82.2; 80.6 and 83.5 days, respectively, and there was less in control by 3.1–7.1 days or 3.3–8.2%. The insemination index in the cows’ control group was 1.5, and in the experimental one – 1.2–1.4, which is 6.7–20.0% less.

The results of mathematical modeling process of melting scrap metal in the bath of an oxygen converter are presented. The influence relative amount of scrap metal in the charge of oxygen-converter smelting and its density on dynamics bath temperature during melting, slag oxidation and liquid metal yield was studied. It is shown that due to change in the shape of scrap metal during its melting, the classical approach to determining the reactive surface area of ​​the latter needs to be clarified.Mathematical descriptions of scrap metal melting in converter smelting by linear dependence and using fourth degree polynomials, which take into account the influence of initial and current carbon concentration in the bath, are offered. The influence of density and fraction of scrap metal, which is a part of metal charge, on duration of its melting in bath of oxygen converter, content iron oxides in slag, temperature mode process and yield liquid metal is investigated. It is shown that increasing mass of scrap metal in the metal charge to 40%, in the absence of its preheating, significantly changes the appearance both the oxidation curves of carbon and the dynamics of the bath temperature in the initial period melting.The latter may be due to the preservation active surface area of ​​scrap metal as its mass changes. Additional heat consumption for melting an increased amount preheated («cold») scrap metal leads to a decrease in the temperature of the liquid bath, which confirms the feasibility using the technology melting with preheating an increased amount of scrap.It is shown that from the point of view ensuring the rational course of converter smelting it is expedient to use equal shares heavy and lightweight scrap metal, regardless of the share latter in the metal charge. In the case using, under the considered conditions, «cold» scrap metal, the maximization yield of liquid metal is provided at the amount scrap up to 22% of the total mass metal charge.

Heat-resistant alloys (superalloys) widely used for manufacturing parts of various components of aircraft engines are complex nickel-based systems which contain apart from alloying (Al, Cr, Co, Ti, Mo, W, etc.) and microalloying additives (B, Mg, REM, etc.) different amounts of the impurities (Mn, Fe, Si, Pb, As, Sn), including gas-forming (O, N, C, S) ones. The use of additive technologies (AT) in manufacturing of complex-shaped parts made of these alloys makes it possible to increase the material utilization coefficient and shorten the technological process. However, the use of AT requires real-time control of the composition of semi-products and finished products at all stages of production. Study of various stages of manufacturing parts from ZhS6K and VZh159 alloys using an AT of selective laser alloying (SLA) is carried out using analytical control systems of the laboratory of the Testing Center (TC) of FSUE «VIAM». A complex of methods for atomic emission, mass spectrometric and X-ray fluorescence determination of different groups of elements was used for the analysis of charge materials, cast bar blanks, metal-powder compositions (MPC) and synthesized parts. The results of analysis of nickel N-1u and chromium Kh99N1 used upon and after smelting of cast billets, as well as analysis of MPC of these alloys carried out by different methods are presented (gas analyzers were used to determine the gas-forming impurities). Monitoring on the chemical composition of materials throughout the process of additive manufacturing ensure their compliance with the regulatory requirements and predict the properties of finished products. The work was carried out within the framework of complex scientific direction 2.1 «Fundamental research» («Strategic directions for the development of materials and technologies for their processing for the period up to 2030»).

In this paper, we discuss one-dimensional differential equation with ω -period. By using the fixed point theory, the existence of a periodic solution is obtained; by using the second Lyapunov method, the uniqueness and stability of the periodic solution are obtained.

Nanowires, atomic point contacts, and chains of atoms are one-dimensional nanostructures, which display size-dependent quantum effects in electrical and thermal conductivity. In this work a Cu nanofilament of a defined resistance and formed between a Cu and Pt electrode is heated remotely in a controlled way. Depending on the robustness of the conductive filament and the amount of heat transferred several resistance-changing effects are observed. In case of sufficiently fragile nanofilament exhibiting electrical quantum conductance effects and moderate heating applied to it, a dramatic increase of resistance is observed just after the completion of the heating cycle. However, when the filament is allowed to cool off, a spontaneous restoration of the originally set resistance of the filament is observed within less than couple tens of seconds. When the filament is sufficiently fragile or the heating too excessive, the filament is permanently ruptured, resulting in a high resistance of the cell. In contrast, for robust, low resistance filaments, the remote heating does not affect the resistance. The spontaneous restoration of the initial resistance value is explained by electron tunneling between neighboring vibrating Cu atoms. As the vibrations of the Cu atoms subside during the cooling off period, the electron tunneling between the Cu atoms becomes more likely. At elevated temperatures, the average tunneling distance increases, leading to a sharp decrease of the tunneling probability and, consequently, to a sharp increase in transient resistance.

Aim. Geometric properties of ice-phobic surfaces are mathematically simulated to provide the anti-icing effect. Methodology. Numerical calculations of droplet motion in the vicinity of a cylinder simulating the leading edge of a wing relies on the use of previously published mathematical models of physical processes. Results. As applied to the problem of icing of aircrafts, the relief configuration of hydrophobic coatings of a solid is estimated in air flow with supercooled droplets, in which liquid drops do not freeze to the streamlined body as a result of collisions with its surface. Research implications. The results of the study can be used to produce a relief of a hydrophobic coating for a specific range of flying vehicle flight conditions.