Effect of viscous dissipation on MHD water-Cu and EG-Cu nanofluids flowing through a porous medium

This paper provides a comparative analysis of two different types of nanofluids for Stokes second problem. Additional effects of MHD, porosity and viscous dissipation are also considered. Two types of Newtonian liquids (water and ethylene glycol) are considered as base fluids with suspended nanosized Cu particles. A homogenous model of Newtonian nanofluids over a flat plate is used to describe this phenomenon with Stokes boundary conditions such that the ambient fluid is static and with uniform temperature. The problem is first written in terms of nonlinear partial differential equations with physical conditions; then after non-dimensional analysis, the Laplace transform method is used for its closed-form solution. Exact expressions are determined for the dimensionless temperature, velocity field, Nusselt number and skin friction coefficient and arranged in terms of exponential and complementary error functions satisfying the governing equations and boundary conditions. They are also reduced to the known solutions of Stokes second problem for Cu-water nanofluids. Results are computed using Maple software. The results showed that both skin friction and rate of heat transfer increase with increasing solid volume fraction of nanoparticles. MHD and porosity had an opposite effect on velocity for both types of nanofluids. The dimensionless temperature increases by increasing the Eckert and Hartmann numbers.

     

Free vibration/buckling analyses of noncylindrical initially compressed helical composite springs

This article presents the use of the stiffness matrix method based on the first-order shear deformation theory to predict the fundamental natural frequencies and buckling loads of noncylindrical unidirectional composite helical springs subjected to initial static axial force and moment. This theoretical study about such springs with circular/rectangular cross-sections and large pitch angles is performed for the first time in the literature. The validity of the present results is verified by the benchmark studies related with initially compressed isotropic cylindrical springs.     

Multiple internal resonances in MEMS arch resonators

Micromachined shallow arch resonant beams have attracted significant attention thanks to their rich dynamical behavior, inherent nonlinearities, and the potential to excite various internal resonances. Currently, there is a lack of comprehensive experimental studies for the various types of internal resonances in arches and particularly at the micro and nano scales. Here, we aim to investigate and identify different types of internal resonances of an initially curved beam, electrothermally actuated and electrostatically driven, by electrical characterization techniques. Upon changing the electrothermal voltage of silicon micromachined arches, the second symmetric natural frequency of an arch is adjusted to near twice, three times, and four times the fundamental natural frequency, which gives rise to 2:1, 3:1, and 4:1 autoparametric resonances between the two modes. These resonances are demonstrated experimentally. We show various frequency-response curves of the total response around the excitation frequency and highlight the contribution of each mode before, during, and after the internal resonances. Allan-deviation results are also shown indicating enhanced frequency stabilization of the arch oscillation when experiencing internal resonances. These studies motivate further research in this direction to exploit internal resonances of micromachined resonators for practical applications, such as sensors and mechanical amplifier.     

The discreteness of the spectrum of the Schrödinger operator equation and some properties of the s‐numbers of the inverse Schrödinger operator

In this article, we investigate the discreteness and some other properties of the spectrum for the Schrödinger operator L defined by the formula on the space L₂(H, [0, ∞)) , where H is a Hilbert space. For the first time, an estimate is obtained for sum of the s‐numbers of the inverse Schrödinger operator. The obtained results were applied to the Laplace's equation in an angular region.     

Numerical solutions of Schrödinger wave equation and Transport equation through Sinc collocation method

Nonlinear Dynamics - This paper focuses on finding soliton solutions for an intrinsic fractional discrete nonlinear electrical transmission lattice. Our investigation is based on the fact that for...     

High-affinity glycopolymer binding to human DC-SIGN and disruption of DC-SIGN interactions with HIV envelope glycoprotein

Noncovalent interactions between complex carbohydrates and proteins drive many fundamental processes within biological systems, including human immunity. In this report we aimed to investigate the potential of mannose-containing glycopolymers to interact with human DC-SIGN and the ability of these glycopolymers to inhibit the interactions between DC-SIGN and the HIV envelope glycoprotein gp120. We used a library of glycopolymers that are prepared via combination of copper-mediated living radical polymerization and azide-alkyne [3+2] Huisgen cycloaddition reaction. We demonstrate that a relatively simple glycopolymer can effectively prevent the interactions between a human dendritic cell associated lectin (DC-SIGN) and the viral envelope glycoprotein gp120. This approach may give rise to novel insights into the mechanisms of HIV infection and provide potential new therapeutics.     

Production of Plant Beneficial and Antioxidants Metabolites by Klebsiella variicola under Salinity Stress

Bacteria that surround plant roots and exert beneficial effects on plant growth are known as plant growth-promoting rhizobacteria (PGPR). In addition to the plant growth-promotion, PGPR also imparts resistance against salinity and oxidative stress and needs to be studied. Such PGPR can function as dynamic bioinoculants under salinity conditions. The present study reports the isolation of phytase positive multifarious Klebsiella variicola SURYA6 isolated from wheat rhizosphere in Kolhapur, India. The isolate produced various plant growth-promoting (PGP), salinity ameliorating, and antioxidant traits. It produced organic acid, yielded a higher phosphorous solubilization index (9.3), maximum phytase activity (376.67 ± 2.77 U/mL), and copious amounts of siderophore (79.0%). The isolate also produced salt ameliorating traits such as indole acetic acid (78.45 ± 1.9 µg/mL), 1 aminocyclopropane-1-carboxylate deaminase (0.991 M/mg/h), and exopolysaccharides (32.2 ± 1.2 g/L). In addition to these, the isolate also produced higher activities of antioxidant enzymes like superoxide dismutase (13.86 IU/mg protein), catalase (0.053 IU/mg protein), and glutathione oxidase (22.12 µg/mg protein) at various salt levels. The isolate exhibited optimum growth and maximum secretion of these metabolites during the log-phase growth. It exhibited sensitivity to a wide range of antibiotics and did not produce hemolysis on blood agar, indicative of its non-pathogenic nature. The potential of K. variicola to produce copious amounts of various PGP, salt ameliorating, and antioxidant metabolites make it a potential bioinoculant for salinity stress management.     

α‐d‐Glucofuranose and α‐d‐allofuranose diacetonides and silyl ether of α‐d‐glucofuranose diacetonide in dithiophosphorylation reactions

α‐d ‐Glucofuranose and α‐d ‐allofuranose diacetonides react with 2,4‐diorganyl 1,3,2,4‐dithiadiphosphetane‐2,4‐disulfides to form optically active dithiophosphonates in 78–81% yields, which are transformed into the corresponding ammonium salts in 90–97% yields by the treatment of n‐hexadecylamine. The S‐silyldithiophosphonate was prepared in 93% yield by the reaction of 2,4‐bis(butoxyphenyl) 1,3,2,4‐dithiadiphosphetane‐2,4‐disulfide with silyl ether of α‐d ‐glucofuranose diacetonide. One of the salts obtained possesses antibacterial activity against Staphylococcus aureus ATCC 6538‐P.