[en] In this research, the hydromagnetic natural convection of an incompressible fluid with point heat source by considering the influence of Hall current and induced magnetic field between infinite vertical walls is studied. The Laplace transform procedure is utilized to determine the analytical solutions of the acquired mathematical model with the wavelet function. With the derived solution of velocity, induced magnetic field, temperature field, and induced current density, the flow character is investigated with the influence of the physical parameters (namely Hall current, Hartmann number, and point heat source) for the presented boundary conditions. Also, the skin friction and volumetric flow rate are derived through the velocity expression. Numerical and graphical results are introduced to formalize the solution of the model. The valuable result from the investigation is that an increase in the length of the point heat source leads to enhance both components of induced current density, induced magnetic field, and primary velocity profiles. Moreover, it is noticeable that an enhancement in the Hall current has a reverse connection with both components of the induced current density, induced magnetic field, while the direct connection with the primary velocity component. There are numerous engineering applications such as the metal cutting, grinding, welding, laser hardening of metals, and many others in which the calculation of temperature field is modelled as a problem involving a point heat source. (author)

[en] The current study is to explore the phenomena of the hydromagnetic free convective flow of an electrically conducting and incompressible viscous fluid through an impermeable vertical cylinder, with the point heat source under the influence of the transversely applied magnetic field of uniform strength in the radial direction. The free convection phenomenon in the working fluid occurs due to the presence of the point/line heat source as it appears in many real-world mechanisms. The main motive of this analytical study is thus to examine the effect of point and line heat source on this buoyancy-dominated developing flow. The governing equations thus framed for the prescribed flow namely energy and momentum, simplify to steady linear differential equations in the physical setup assumed in this investigation. These equations, in non-dimensional forms, have been solved, in turn, employed simultaneous ordinary differential equations (ODEs) theory. The resulting closed form solutions for the physical variables, namely fluid temperature and fluid velocity have been presented in terms of Bessel, modified Bessel, and Regularized Hypergeometric functions. Additionally, skin friction coefficient, Nusselt number, and mass flow rate are numerically discussed for the involved parameters. There arises a number of pertinent physical parameters in our analysis: Heat source, Hartman number, and point heat source whose influence on the developing velocity and some temperature profiles have been illustrated through a number of plots. Major outcomes show that the enhancement in Hartmann number motivates a reduction in the velocity profile for the point and line heat source cases. In addition, the fluid motion rises due to the line and point heat source, and the velocity and temperature profiles have a higher value in the case of the line heat source as compared to the point heat source. (author)

[en] Highlights: • ESIPT mechanism and C=N isomerization mechanism based fluorometric sensor was presented. • Sensing property towards Al³⁺ metal ion among other metal ions was analyzed. • Pyrimidine based sensor has high affinity and sensitivity for Al³⁺ ion. - Abstract: 6-amino-5-(((2-hydroxynaphthalen-1-yl)methylene)amino)-2-mercaptopyrimidin-4-ol (L1) and 6-amino-5-((4-bromobenzylidene)amino)-2-mercaptopyrimidin-4-ol (L2) have been designed and characterized by various techniques such as UV–Vis, fluorescence, FT-IR, mass spectrometry and NMR spectroscopy. L1 was successfully applied for selective recognition of aluminum ion and showed “OFF-ON type” mode in the presence of Al³⁺ ion. The sensor was recommended for the selective detection of Al³⁺ with 1:1 stoichiometry by Job's plot in ACN medium. The high sensitivity of host L1 supports the high detection limit, 99 nM with good association constant. It was also used for bacterial cell imaging (E.coli DHα) and logic gate applications which was manifested the green and red fluorescent images with Al³⁺ion and represents INHIBIT logic gate in switching behavior.

[en] We are very aware of the importance of the ozone layer, without which life on the Earth would not have evolved in the way it has. Solar storms carry energetic protons into the Earth’s upper atmosphere, where they boost production of nitrogen oxides which are known as ozone killers and which ultimately increase ultraviolet (UV) radiations. In the present study, we estimate the effects of solar energetic protons during super storms (Dst index < –300 nT over the total ozone column for the last 32 yr. We select a total of seven super storm events that occurred during solar cycles 22–24 (for the last 32 yr) having Dst index < –300 nT. To that end, we apply superposed epoch analysis (SEA) to verify the impact of storm events on the quantitative variation of total ozone column and on UV radiations during super storm events. After completing the empirical analysis, we conclude that the ozone column gets depleted significantly (22±6.8%) as proton density increases during super storm events and this decrement in the ozone level is further responsible for a substantial increase (26±11.2%) in peak UV radiation intensities. (paper)

[en] The influence of a point heat source and Hall current on the laminar hydromagnetic free convective flow of an incompressible and electrically conducting viscous liquid between two vertical walls has been studied. A wavelet function is utilised to mathematically formulate the point or line heat source. The incidental equations on the flow have been processed subject to the Boussinesq approximation. A unified analytical solution of basic equations like thermal energy and momentum has been derived by employing Laplace transform technique. The impacts of the pertinent physical parameters, such as Hall parameter, magnetic field and point heat source, on the velocity field are explained graphically. The valuable result from the investigation is that an increase in the length of the point heat source leads to the enhancement of the velocity profiles. Moreover, it is noticeable that an enhancement of Hall current has a direct connection with the primary factor of the volumetric flow rate and skin friction. (author)

[en] The repetitive soil slope failure along the National Highway (NH)-5 in Jhakri region of Himachal Pradesh, India draws frequent concern due to heavy damage and traffic disruption almost every year. Being only linking route from border district to the nearby land area, stability of the road-cut slopes along this highway is of major concern in regard to safe transportation. Absence of any previous stability investigation of this recurring slope failure calls for an integrated geotechnical and numerical approach in order to understand the instability factors. The geotechnical analysis has been performed to determine the inherent properties of soil materials which affect the stability of existing slope. An event-specific antecedent rainfall threshold has been suggested to quantify the relationship between rainfall and slope failure. A two-dimensional limit equilibrium method has also been executed to visualize the scenario of pre- and post-failure stability of the slope. On the basis of limit equilibrium analysis, it has been inferred that slope geometry is a major affecting parameter that influences the failure pattern. Moreover, preventive measures through benching and soil nailing have also been proposed and validated through limit equilibrium analysis for long-term stability and safe transportation.

[en] Kinetics of oxidation of lactose by (Cu(bipy)₂)²⁺ in alkaline medium using Ru(III) as an inhibitor has been studied spectrophotometrically at 40 °C. The studies show that the rate of the reaction is zero order with respect to (Cu(bipy)₂)²⁺ and first order with respect to (lactose). The order of reaction is found to be two at low concentrations of OH^- (from 1.48×10⁵ to 3.47×10⁵ M) and less than two at its high concentrations (from 4.27×10⁵ to 6.31×10⁵ M). There is a substantial decrease in the pseudo-zero order rate constant with increase in the concentration of Ru(III) chloride, indicating the role of Ru(III) chloride as an inhibitor. Decrease in the rate with increase in dielectric constant of the medium is observed, while ionic strength of the medium and bipyridyl concentration has no influence on the rate. Based on kinetic data and spectrophotometric evidences, a suitable mechanism is proposed for the studied reaction. (author)

[en] We report a first-principles density functional theory study of the B2 phase structure in the Ti-25Al-25Zr alloy. Several structural models with different site occupancies have been investigated. In the ideal B2 phase, the Zr atom is found to preferentially occupy the Ti site. However, if the atoms are allowed to relax, Zr occupies both Ti and Al sites, leading to local positional disorder in the structure due to the large size differences of the constituent elements. Further, this alloy is predicted to have better room temperature ductility, enhancing its utility in several technological applications.

[en] Graphical abstract: Variation of potential with Be²⁺ activity for membrane sensors based on dibenzo(perhydrotriazino)aza-14-crown-4 ether. Highlights: ► It is the first report on an ion sensor using substituted aza-14-crown-4 for Be²⁺. ► Response time is 15 s and life time is more than 4 months with good reproducibility. ► The proposed electrode works well in a wide pH range 3.0–9.0. - Abstract: Beryllium(II) selective electrodes have been fabricated based on poly(vinyl chloride) (PVC) matrix membranes containing newly synthesized neutral carrier dibenzo(perhydrotriazino)aza-14-crown-4 ethers as ionophore. Best performance was exhibited by the membrane having a composition ionophore (IIa):PVC:sodium tetraphenylborate (NaTPB):tributyl phosphate (TBP) in the ratio (w/w; mg) of 5:30:3:65. This membrane worked well over a wide concentration range 7.6 × 10⁻⁶ to 1.0 × 10⁻¹ M of Be²⁺ with a Nernstian slope of 30.7 mV per decade of beryllium activity. The response time of the sensor is 15 s and the membrane can be used over a period of 4 months with good reproducibility. The proposed electrode works well in a wide pH range 3.0–9.0. It was successfully applied to the determination of beryllium in a mineral sample.

[en] A novel gadolinium selective coated graphite electrode based on 2,6-bis-[1-{N-cyanopropyl,N-(2-methylpridyl)}aminoethyl]pyridine [P] is described. The best performance was exhibited by the electrode having membrane composition P:NaTPB:PVC:NPOE as 8:4:30:58 (%, w/w). The electrode demonstrates excellent potentiometric characteristics towards gadolinium ion over several interfering ions. The electrode exhibited a Nernstian response to Gd³⁺ ion over a wide concentration range 2.8 x 10^-7 to 5.0 x 10^-2 M with a detection limit (6.3 ± 0.1) x 10^-8 M and slope 19.6 ± 0.1 mV decade^-1 of a_Gd³⁺. Furthermore, it showed a fast response time (12 s) and can be used for 2.5 months without significant divergence in its characteristics. Noticeably, the electrode can tolerate the concentration of different surfactants up to 1.0 x 10^-4 M and can be used successfully in 30% (v/v) ethanol media and 10% (v/v) methanol and acetonitrile water mixture. The useful pH range of this sensor is 2.0 to 8.0. It is sufficiently selective and can be used for the determination of Gd³⁺ ions in waste water and rock samples. It also serves as a good indicator in the potentiometric titration of GdCl₃ with EDTA.