Impact of melting heat transfer in the time-dependent squeezing nanofluid flow containing carbon nanotubes in a Darcy-Forchheimer porous media with Cattaneo-Christov heat flux

This study aims to investigate the time-dependent squeezing of nanofluid flow, comprising carbon nanotubes of dual nature, e.g. single-walled carbon nanotubes, and multi-walled carbon nanotubes,between two parallel disks. Numerical simulations of the proposed novel model are conducted,accompanied by Cattaneo-Christov heat flux in a Darcy-Forchheimer permeable media. Additional impacts of homogeneous–heterogeneous reactions are also noted, including melting heat. A relevant transformation procedure is implemented for the transition of partial differential equations to the ordinary variety. A computer software-based MATLAB function, bvp4c, is implemented to handle the envisioned mathematical model. Sketches portraying impacts on radial velocity, temperature, and concentration of the included parameters are given, and deliberated upon. Skin friction coefficient and local Nusselt number are evaluated via graphical illustrations. It is observed that the local inertia coefficient has an opposite impact on radial velocity and temperature field. It is further perceived that melting and radiation parameters demonstrate a retarding effect on temperature profile.     

Significance of activation energy and Wu's slip features in Cross nanofluid with motile microorganisms

The current article investigates the impact of the bioconvection in an unsteady flow of magnetized Cross nanofluid with gyrotactic microorganisms and activation energy over a linearly stretched configuration. The analysis has been performed by utilizing the realistic Wu's slip boundary and zero mass flux conditions. The effects of nonlinear thermal radiation and the activation energy are also addressed. The governing flow equations are deduced to a dimensionless form by considering suitable transformations which are numerically targeted via a shooting algorithm. The physical visualization of each physical parameter governing the flow problem has been displayed graphically for distribution of velocity, temperature, concentration and motile microorganisms. The numerical treatment for the variation of skin friction coefficient, local Nusselt number, local Sherwood number and motile density number is performed in tabular forms.     

Static anti-windup compensator design for nonlinear time-delay systems subjected to input saturation

Nonlinear Dynamics - In this paper, a novel technique for synthesizing static anti-windup compensator (AWC) is explored for dynamic nonlinear plants with state interval time-delays, exogenous input...     

Adsorption Behavior and Dynamic Interactions of Anionic Acid Blue 25 on Agricultural Waste

In this study, adsorption characteristics of a negatively charged dye, Acid Blue 25 (AB25), on pomelo pith (PP) was studied by varying the adsorption parameters, with the aim of evaluating the adsorption mechanism and establishing the role of hydrogen bonding interactions of AB25 on agricultural wastes. The kinetics, intraparticle diffusion, mechanism, and thermodynamics of the AB25 adsorption were systematically evaluated and analyzed by pseudo-first-order and pseudo-second-order kinetic models, the Weber–Morris intraparticle and Boyd mass transfer models, the Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin isotherm models, and the Van’t Hoff equation. It was found that AB25 adsorption followed pseudo-second-order kinetics, governed by a two-step pore-volume intraparticle diffusion of external mass transfer of AB25 onto the PP surface. The adsorption process occurred spontaneously. The adsorption mechanism could be explained by the Langmuir isotherm model, and the maximum adsorption capacity was estimated to be 26.9 mg g⁻¹, which is comparable to many reported adsorbents derived from agricultural wastes. Changes in the vibrational spectra of the adsorbent before and after dye adsorption suggested that AB25 molecules are bound to the PP surface via electrostatic and hydrogen bonding interactions. The results demonstrated that the use of pomelo pith, similar to other agricultural wastes, would provide a basis to design a simple energy-saving, sustainable, and cost-effective approach to remove negatively charged synthetic dyes from wastewater.     

Two stereoisomeric pentacyclic oxin­dole alkaloids from Uncaria tomentosa: uncarine C and uncarine E

The chloro­form solvate of uncarine C (pteropodine), (1′S,3R,4′aS,5′aS,10′aS)‐1,2,5′,5′a,7′,8′,10′,10′a‐octa­hydro‐1′‐methyl‐2‐oxospiro­[3H‐indole‐3,6′(4′aH)‐[1H]­pyrano­[3,4‐f]indolizine]‐4′‐carboxyl­ic acid methyl ester, C₂₁H₂₄N₂O₄·CHCl₃, has an absolute configuration with the spiro C atom in the R configuration. Its epimer at the spiro C atom, uncarine E (isopteropodine), (1′S,3S,4′aS,5′aS,10′aS)‐1,2,5′,5′a,7′,8′,10′,10′a‐octahydro‐1′‐methyl‐2‐oxospiro[3H‐indole‐3,6′(4′aH)‐[1H]pyrano[3,4‐f]indolizine]‐4′‐carboxylic acid methyl ester, C₂₁H₂₄N₂O₄, has Z′ = 3, with no solvent. Both form intermolecular hydrogen bonds involving only the ox­indole, with N?O distances in the range 2.759 (4)–2.894 (5) Å.     

Single Unit Cell Bismuth Tungstate Layers Realizing Robust Solar CO2 Reduction to Methanol

Solar CO₂ reduction into hydrocarbons helps to solve the global warming and energy crisis. However, conventional semiconductors usually suffer from low photoactivity and poor photostability. Here, atomically‐thin oxide‐based semiconductors are proposed as excellent platforms to overcome this drawback. As a prototype, single‐unit‐cell Bi₂WO₆ layers are first synthesized by virtue of a lamellar Bi‐oleate intermediate. The single‐unit‐cell thickness allows 3‐times larger CO₂ adsorption capacity and higher photoabsorption than bulk Bi₂WO₆. Also, the increased conductivity, verified by density functional theory calculations and temperature‐dependent resistivities, favors fast carrier transport. The carrier lifetime increased from 14.7 to 83.2 ns, revealed by time‐resolved fluorescence spectroscopy, which accounts for the improved electron‐hole separation efficacy. As a result, the single‐unit‐cell Bi₂WO₆ layers achieve a methanol formation rate of 75 μmol g^?1 h^?1, 125‐times higher than that of bulk Bi₂WO₆. The catalytic activity of the single‐unit‐cell layers proceeds without deactivation even after 2 days. This work will shed light on designing efficient and robust photoreduction CO₂ catalysts.     

Recent trends in ring opening of epoxides by amines as nucleophiles

β-Amino alcohols are versatile intermediates in the synthesis of various biologically potent compounds, which can also be achieved by ring opening of epoxides by amines. In the present review, focus has been placed on the ring opening of epoxides with amines under a variety of reaction parameters reported during 2011–2015. All the factors that resulted in excellent yields and high regioselectivity, are environmentally benign, and use mild conditions have been discussed in detail. In addition, the applications of these methods in the synthesis of biologically active compounds such as β-blockers have also been described.     

Chemical profiling and standardization of Lepidium meyenii (Maca) by reversed phase high performance liquid chromatography

Lepidium meyenii (Maca) is one of the few plants that can be cultivated in the harsh climate of the Andes. Its nutritious hypocotyl is traditionally used as food and medicine, and Maca products are increasingly becoming popular in the western world as tonics. This paper describes the first analytical method allowing the determination of the main macamides and macaenes, the marker compounds of L. meyenii. A separation within 35 min was possible by using a C-12 stationary phase, an acidic mobile phase comprising of acetonitrile and water, and raising the column temperature to 40 degrees C. By monitoring the separation at 210 and 280 nm, the markers were detectable as low as 0.40 microg/ml. In order to validate the method, accuracy, precision, linearity, limit of detection and intra/inter day repeatability were determined. The analysis of several commercially available Maca products showed a similar qualitative pattern but significant differences in the quantitative composition. The percentage of total markers in the preparations varied from 0.15 to 0.84%, resulting in daily intakes for the consumer from 1.52 to 14.88 mg, respectively.     

Comparative Analysis of Microbial Consortiums and Nanoparticles for Rehabilitating Petroleum Waste Contaminated Soils

Nano-bioremediation application is an ecologically and environmentally friendly technique to overcome the catastrophic situation in soil because of petroleum waste contamination. We evaluated the efficiency of oil-degrading bacterial consortium and silver nanoparticles (AgNPs) with or without fertilizer to remediate soils collected from petroleum waste contaminated oil fields. Physicochemical characteristics of control soil and petroleum contaminated soils were assessed. Four oil-degrading strains, namely Bacillus pumilus ({"type":"entrez-nucleotide","attrs":{"text":"KY010576","term_id":"1248281175"}}KY010576), Exiguobacteriaum aurantiacum ({"type":"entrez-nucleotide","attrs":{"text":"KY010578","term_id":"1248281177"}}KY010578), Lysinibacillus fusiformis ({"type":"entrez-nucleotide","attrs":{"text":"KY010586","term_id":"1248281185"}}KY010586), and Pseudomonas putida ({"type":"entrez-nucleotide","attrs":{"text":"KX580766","term_id":"1159332275"}}KX580766), were selected based on their in vitrohydrocarbon-degrading efficiency. In a lab experiment, contaminated soils were treated alone and with combined amendments of the bacterial consortium, AgNPs, and fertilizers (ammonium nitrate and diammonium phosphate). We detected the degradation rate of total petroleum hydrocarbons (TPHs) of the soil samples with GC-FID at different intervals of the incubation period (0, 5, 20, 60, 240 days). The bacterial population (CFU/g) was also monitored during the entire period of incubation. The results showed that 70% more TPH was degraded with a consortium with their sole application in 20 days of incubation. There was a positive correlation between TPH degradation and the 100-fold increase in bacterial population in contaminated soils. This study revealed that bacterial consortiums alone showed the maximum increase in the degradation of TPHs at 20 days. The application of nanoparticles and fertilizer has non-significant effects on the consortium degradation potential. Moreover, fertilizer alone or in combination with AgNPs and consortium slows the rate of degradation of TPHs over a short period. Still, it subsequently accelerates the rate of degradation of TPHs, and a negligible amount remains at the end of the incubation period.     

A Novel Application of Multi-Resonant Dissipative Elastic Metahousing for Bearings

Bearing as an important machine element is widely used for industrial and auto-motive applications.At certain operational speed,bearings induce disturbing vibra...