Technological Features of the Liquid-Solid State of the Boundary Layer in the Processes of Bimetallic Products

The hydrodynamic and thermal state in the contact zone of the layers of a bimetallic product obtained by pouring liquid iron onto a solid steel billet, which changes in time and is responsible for the strength of the diffusion joint and the geometric parameters of the transition layer, has been investigated. Simplified analytical dependences, mathematical modeling data and experimental results of the liquid phase existence time in the contact zone based on research of the melt velocities during pouring and changes in the thermal field are presented. It is shown that simplified calculations data coincide in order and are close in values ​​to the calculations of mathematical modeling and experimental data, which makes it possible to use them for preliminary rough estimates by technologists and metallurgists.

Effects of Potassium Silicate Fertilizer on Photosynthetic Characteristics and Yield in Winter Wheat (Triticum Aestivum L.)

Effects of different dosages of potassium silicate fertilizer on photosynthetic characteristics and yield of winter wheat under field conditions were studied. Four different dosages: 0, 45, 90 and 135kg/ha were applied. Results showed that the chlorophyll content, net photosynthetic rate of wheat flag leaf firstly increased and then decreased with the increase of levels of potassium silicate fertilizer. By the change of SPAD values after flowering, when the application of potassium silicate fertilizer was 90 kg/ha, the existence time of chlorophyll in flag leaf was significantly long, and the net photosynthetic rate was significantly increased. The 1000-grain weight of winter wheat significantly increased and the yield the highest. Overall, when the applied amount of potassium silicate fertilizer was 90 kg/ha, the performances of winter wheat were best. Bangladesh J. Bot. 50(4): 1127-1132, 2021 (December)

Extended lifespan of the fractional BBM equation

For 0 < α < 1, N ⩾ 2 and with initial data ‖ u 0 ‖ H N + α 2 = ε, sufficiently small, we show that the existence time for solutions of the fractional BBM equation ∂ t u + ∂ x u + u ∂ x u + | D | α ∂ t u = 0, can be extended from the hyperbolic existence time 1 ε to 1 ε 2 . For the proof we use a quasilinear modified energy method, based on a normal form transformation as in Hunter, Ifrim, Tataru, Wong (Proc. Am. Math. Soc., 143(8) (2015) 3407–3412).

Study on Time Characteristics of Coupling Discharge in Pulsed Laser Induced Double-TIG Welding

Based on the dynamic behavior of laser keyhole, the time characteristics of coupling discharge of heat source in pulsed laser induced double-TIG welding (LIDTW) are studied. The behaviors of arc plasma and laser keyhole were directly observed by high-speed camera and auxiliary illumination source. The physical characteristics of arc plasma were analyzed by spectrometer and arc quality analyzer. A physical model is established to reveal the regulation mechanism of time characteristics of coupling discharge. It is found that after laser pulse action the coupling discharge between keyhole plasma and double-arc plasma does not end immediately, and its time depends on the existence time of keyhole. During hybrid welding, when the combined force of arc pressure and Marangoni force can overcome the gravity, the liquid metal is forced out of the keyhole and the keyhole remains open. Improving the electron density of arc plasma and arc voltage and reducing the diameter of arc conductive channel by selecting appropriate parameters to is the key to prolong the existence time of keyhole, which is beneficial to improve the welding penetration. The coupling enhancement of double-arc electromagnetic field in LIDTW can effectively suppress keyhole backfill and increase the duty ratio of coupling discharge. When the total current intensity is 200 A, compared with laser induced single-TIG welding (LISTW), the existence time of keyhole in LIDTW increases by 77 %, the duty ratio of coupling discharge increases by 12 %, and the weld penetration increases by 29.2 %.

Functional Effects In Silico Prediction for Androgen Receptor Ligand-Binding Domain Novel I836S Mutation

Over 1000 mutations are described in the androgen receptor (AR) gene. Of those, about 600 were found in androgen insensitivity syndrome (AIS) patients, among which 400 mutations affect the ligand-binding domain (LBD) of the AR protein. Recently, we reported a novel missense mutation c.2507T>G I836S (ClinVarID: 974911) in a patient with complete AIS (CAIS) phenotype. In the present study, we applied a set of computational approaches for the structural analysis of the ligand-binding domains in a wild-type and mutant AR to evaluate the functional impact of the novel I836S mutation. We revealed that the novel I836S substitution leads to a shorter existence time of the ligand’s gating tunnel and internal cavity, occurring only in the presence of S836 phosphorylation. Additionally, the analysis of phosphorylation of the 836 mutant residues explained the negative impact on AR homodimerization, since monomer surface changes indirectly impacted the binding site. Our analyses provide evidence that I836S causes disruptions of AR protein functionality and development of CAIS clinical features in patients.

Detonation nanodiamonds: from synthesis theory to application practice

The review is devoted to the current state of research and advances in the production and study of the properties of detonation nanodiamonds (DND), their application in technology and medicine. New data on the theory and practice of DND synthesis for the last 1–5 years are considered and systematized. It is shown that the zone of chemical reactions (ZCR) during the blust of explosive materials (EM) is decisive for the fractal pre-diamond structure formation, the final region of the nanodiamonds (1/3–3/4 of the diameter of the explosive charge) formation is determined. The possibility of predicting the DND yield and the influence of parameters on the synthesis process of nanodiamonds from individual EMs of binary and ternary compositions is shown, their optimal formulations are determined. The optimal ZCR width and the existence time of chemical reactions have been identified. The dependence of the DND yield on the nitrogen content in the EM was shown. The most effective method of DND purification and the possibility of obtaining graphite-diamond compositions of a given formulation are presented. The most informative indicators of nanodiamonds characterization are given. The magnetic properties of nanodiamonds are considered and the identity of the properties of DNDs from different EMs is shown. The characteristics of new compositions based on DND are indicated: electrochemical coatings (gold and chromium-diamond), thermal pastes, diamond-containing polymer filaments for a 3D printer, fuel compositions, enterosorbents, compatible with biosystems of the nanodiamond-drug composition.

Linear stability of blowup solution of incompressible Keller–Segel–Navier–Stokes system

In this paper, we consider the linear stability of blowup solution for incompressible Keller–Segel–Navier–Stokes system in whole space $\mathbb{R}^{3}$ R 3 . More precisely, we show that, if the initial data of the three dimensional Keller–Segel–Navier–Stokes system is close to the smooth initial function $(0,0,\textbf{u}_{s}(0,x) )^{T}$ ( 0 , 0 , u s ( 0 , x ) ) T , then there exists a blowup solution of the three dimensional linear Keller–Segel–Navier–Stokes system satisfying the decomposition $$ \bigl(n(t,x),c(t,x),\textbf{u}(t,x) \bigr)^{T}= \bigl(0,0, \textbf{u}_{s}(t,x) \bigr)^{T}+\mathcal{O}(\varepsilon ), \quad \forall (t,x)\in \bigl(0,T^{*}\bigr) \times \mathbb{R}^{3}, $$ ( n ( t , x ) , c ( t , x ) , u ( t , x ) ) T = ( 0 , 0 , u s ( t , x ) ) T + O ( ε ) , ∀ ( t , x ) ∈ ( 0 , T ∗ ) × R 3 , in Sobolev space $H^{s}(\mathbb{R}^{3})$ H s ( R 3 ) with $s=\frac{3}{2}-5a$ s = 3 2 − 5 a and constant $0< a\ll 1$ 0 < a ≪ 1 , where $T^{*}$ T ∗ is the maximal existence time, and $\textbf{u}_{s}(t,x)$ u s ( t , x ) given in (Yan 2018) is the explicit blowup solution admitted smooth initial data for three dimensional incompressible Navier–Stokes equations.

Effects of slide-to-roll ratio and varying velocity on the lubrication performance of grease at low speed

Under steady-state pure rolling conditions with low speed, the thickener fiber agglomerations can be maintained for a long time, generating a beneficial thicker film thickness. However, in industrial applications, motions with sliding or transient effects are very common for gears, rolling-element bearings or even chain drives, evaluation of the grease performance under such conditions is vital for determining the lubrication mechanism and designing new greases. In this project, optical interferometry experiments were carried out on a ball-disk test rig to study the disintegration time of the grease thickener agglomerations with the increase of the slide-to-roll ratio under steady-state and reciprocation motions. Under steady-state conditions, the thickener fiber agglomeration can exist for a while and the time becomes shorter with the increase of the slide-to-roll ratio above the critical speed. Below the critical speed, the thickener fiber can exist in the contact in the form of a quite thick film for a very long time under pure rolling conditions but that time is decreased with the increase of the slide-to-roll ratio. The introduction of the transient effect can further reduce the existence time of the thickener.

THE THEME OF BESIEGED LENINGRAD IN THE LETTERS OF OLGA FREINDENBERG TO BORIS PASTERNAK IN THE FIRST HALF OF THE 1940S

The theme of besieged Leningrad contained in the letters of scholar-philologist, culture scientist Olga Freindenberg to her cousin Boris Pasternak is analysed in the paper. Since the correspondence was published relatively recently, its introduction to scientifi c circulation, determination of the subject and intentions of the correspondents seem to be important and topical. The article is intended for specialists-philologists, for all those interested in epistolary heritage of the 20th century. The correspondence between Boris Pasternak and Olga Freindenberg referring to the period of the siege is represented by the author as a specifi c type of combined discourse which unite social and communicative, everyday, signifi cant and symbolic functions. It is a part of the single artistic and semantic canvas, the whole creative heritage of the cousins, the whole of their correspondence which lasted for more than half a century and was based on «everlasting» themes like creative work, meaning of existence, love, faith, humanism. The image of besieged Leningrad is represented in the letters as a starting point for correspondents’ philosophic considerations about such categories as existence, time and space, about meaning of existence. At the same time, the letters demonstrate their authors’ artistic talent and virtuous possession of the word, the ability to say important between the lines. The stylistics of Olga Freidenberg’s epistolary heritage, when syntax, along with lexical fi gurative, gives rise to vivid, tragic paintings of what is described, is analysed in the work.

Review of the volume „Timpul in filosofie si stiinta” [Time in philosophy and science], author: Andreea Elena Matic, Lumen Publishing House, 2017

The volume "Time in philosophy and science", published in 2017 by Lumen Publishing House from Iasi, Romania, is a meeting with the books and time, more precisely with time in philosophy and science, as the author, Andreea Elena Matic proposes us to agree on relativity, but also on the absolute of time. Time is an obsession of each of us because it is never enough for us. Time is personified as an incarnation of the divinity or, on the contrary, an incarnation of the infernal, of the less elevated area of us and of all the universe. We all have concerns about what time means in the area of magic, esotericism, science, about how to run away from its passage, or from our passage through time. Time is a fountain, time is an eternal return, time is safe and linear, an endless continuity of existence, time is what we all try to steal or lose.