A heuristic procedure for the Capacitated m-Ring-Star problem

In this paper we propose a heuristic method to solve the Capacitated m-Ring-Star Problem which has many practical applications in communication networks. The problem consists of finding m rings (simple cycles) visiting a central depot, a subset of customers and a subset of potential (Steiner) nodes, while customers not belonging to any ring must be “allocated” to a visited (customer or Steiner) node. Moreover, the rings must be node-disjoint and the number of customers allocated or visited in a ring cannot be greater than the capacity Q given as an input parameter. The objective is to minimize the total visiting and allocation costs. The problem is a generalization of the Traveling Salesman Problem, hence it is NP-hard. In the proposed heuristic, after the construction phase, a series of different local search procedures are applied iteratively. This method incorporates some random aspects by perturbing the current solution through a “shaking” procedure which is applied whenever the algorithm remains in a local optimum for a given number of iterations. Computational experiments on the benchmark instances of the literature show that the proposed heuristic is able to obtain, within a short computing time, most of the optimal solutions and can improve some of the best known results.     

The effect of Dirac phase on acoustic vortex in media with screw dislocation

We study acoustic vortex in media with screw dislocation using the Katanaev–Volovich theory of defects. It is shown that the screw dislocation affects the beam?s orbital angular momentum and changes the acoustic vortex strength. This change is a manifestation of topological Dirac phase and is robust against fluctuations in the system.     

Synthesis of Hexahydrospiro[pyrazolo[3,4‐b]quinoline‐4,1′‐pyrrolo[3,2,1‐ij]quinoline‐2′,5(1H,4′H)‐diones] from 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione Using Fe3O4@Cu(OH)x as a Nanocatalyst

The tricyclic isatin, 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione, undergoes three‐component, one‐pot reactions with 1‐aryl‐3‐methylpyrazole‐5‐amines and cyclohexane‐1,3‐diones producing hexacyclic spiro products, hexahydrospiro[pyrazolo[3,4‐b]quinoline‐4,1‐pyrrolo[3,2,1‐ij]quinoline‐2′,5(1H,4′H)‐diones]. Comparable spiro condensation products are also obtained using 4‐hydroxy‐2H‐1‐benzopyran‐2‐one in place of cyclohexane‐1,3‐diones.     

Numerical analysis of the internal flow and the mixing chamber length effects on the liquid film thickness exiting from the effervescent atomizer

Journal of Thermal Analysis and Calorimetry - Two-phase flow was simulated within the effervescent atomizer by the volume of fluid interface tracing model. Different gas-to-liquid mass ratios...     

Polyphenolic profiling of Ipomoea carnea Jacq. by HPLC-DAD and its implications in oxidative stress and cancer

Ipomoea carnea Jacq. is an important folklore medicinal plant, assessed for its underexplored biological potential. Antioxidant, cytotoxic, antiproliferative and polyphenolic profile of whole plant was evaluated using various techniques. Maximum extract recovery (29% w/w), phenolic [13.54 ± 0.27 μg GAE/mg dry weight (DW)] and flavonoid (2.11 ± 0.10 μg QE /mg DW) content were recorded in methanol-distilled water (1:1) flower extract. HPLC-DAD analysis quantified substantial amount of six different polyphenols ranging from 0.081 to 37.95 μg/mg extract. Maximum total antioxidant and reducing potential were documented in methanol-distilled water and acetone-distilled water flower extracts (42.62 ± 0.47 and 24.38 ± 0.39 μg AAE/mg DW) respectively. Ethanol-chloroform root extract manifested highest free radical scavenging (IC₅₀ of 61.22 μg/mL) while 94.64% of the extracts showed cytotoxicity against brine shrimps. Ethanol leaf extract exhibited remarkable activity against THP-1 cell line (IC₅₀ = 8 ± 0.05 μg/mL) and protein kinases (31 mm phenotype bald zone).     

Nanogram/mL detection of nortriptyline: Preparation of a molecularly imprinted polymer for spectrophotometric determination of nortriptyline based on multivariate optimization methods

In this work, the molecularly imprinted polymer was used as a selective sorbent in solid‐phase extraction method for the spectrophotometric determination of nortriptyline at 239 nm. Molecularly imprinted polymer was synthesized by pyrrole as a functional monomer in the presence of nortriptyline as a template. Several factors, consist of the concentration of the monomer to template ratio, amount of initiator, stirring rate, reaction time, the pH of the buffer solution, amount of sorbent, loading time, shaking rate of loading, extraction time, and shaking rate of extraction were evaluated due to their effectiveness in the preparation and extraction capability of molecularly imprinted polymer. Multivariate optimization methods, such as Plackett‐Burman and central composite designs, were employed to find and optimize the significant factors. Under the selected optimal conditions, molecularly imprinted polymer showed a linear range from 0.1 to 100 µmol/L (0.026 to 26 µg/mL) nortriptyline, a detection limit of 10.3 nmol/L (2.7 ng/mL), a highly repeatable (relative standard deviation of 3.7%) and reproducible response (relative standard deviation of 4.6%), and a good selectivity in the presence of structurally related molecules. Furthermore, molecularly imprinted polymer showed high extraction efficiency and was successfully used for the determination of nortriptyline in real samples.     

Application of ion-imprinted polymer synthesized by precipitation polymerization as an efficient and selective sorbent for separation and pre-concentration of chromium ions from some real samples

In this study, a new Cr(III)-imprinted polymer (Cr(III)-IIP) is prepared from CrCl₃·6H₂O, methacrylic acid functional monomer, ethyleneglycoldimethacrylate cross-linking agent, 2,2?-azobisisobutyronitrile radical initiator and 2,2-(azanediylbis (ethane-2,1-diyl))bis(isoindoline-1,3-dione) ligand. To obtain the maximum adsorption capacity, the optimum condition was studied through pH, type and concentration of eluent, IIP weight, sample volume as well as the adsorption and desorption times. The Cr(III) ion content was determined via flame atomic absorption spectrometer. In optimum conditions, the adsorption capacity of the IIP for Cr(III) was obtained to be 74.65 mg g^?1, using 50 mg of IIP and the initial pH solution of 3.0. Both the adsorption and desorption times for quantitative analyses of Cr(III) ions were 15 and 5 min; respectively. After elution of the adsorbed ions by 3 mL of 4 mol L^?1 HNO₃ aqueous solution, the established IIP-based SPE procedure provides a reasonable pre-concentration factor of 100. The IIP-based pre-concentration method provides a low detection limit of 1.7 µg L^?1 with good repeatability (RSD?=?3.22%). Reusability studies confirmed that synthesis IIP is reusable and recoverable up to six cycles. According to the selectivity experiments, it was concluded that the prepared sorbent possesses more affinity toward Cr(III) ions than other ions such as Al³⁺, Pb²⁺, Cu²⁺, Mn²⁺, Fe²⁺, Zn²⁺, and Ni²⁺ ions. To evaluate the potential applicability of the proposed separation method, the pre-concentration and determination of trace amounts of Cr(III) were performed successfully in food samples with complex matrices, a bestial sample (i.e. cow liver) and an herbal product (i.e., broccoli) as real samples.     

Zinc(II)-poly(urea-formaldehyde) supported on magnetic nanoparticles: A hybrid nanocatalyst for green synthesis of spiropyrans,spiroxanthenes, and spiropyrimidines

Immobilization of metal ions onto inorganic supports has very interesting biological, industrial, and catalysis applications. In this study, CoFe₂O₄@SiO₂@PUF@Zn(OAc)₂ nanostructure was successfully fabricated by immobilization of zinc acetate on the surface of poly(urea-formaldehyde) supported on magnetic CoFe₂O₄@SiO₂ nanoparticles through a layer-by-layer assembly. The structure of hybrid nanoparticles was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, energy-dispersive X-ray spectroscopy, inductively coupled plasma atomic emission spectroscopy, vibrating sample magnetometry, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy, and transmission electron microscopy. Zinc-poly(urea-formaldehyde) supported on magnetic nanoparticles (MNPs@SiO₂@PUF@Zn) was successfully used for the synthesis of spirooxindolopyran and spirooxindoloxanthene derivatives in aqueous medium as an environmentally benign condition. High yields, short reaction times, green solvent, reusability without significant reduction in catalytic activity, and simple separation of the catalyst using an external magnet along with environmental compatibility are some benefits of this procedure.     

Synthesis and pharmacological properties of polysubstituted 2-amino-4H-pyran-3-carbonitrile derivatives

Molecular Diversity - 2-Amino-3-cyano-4H-chromenes are structural core motifs that received increasing attention in the last years due to their interesting potential pharmacological properties. In...