Low frequency ultrasound and UV-C for elimination of pathogens in recirculating aquaculture systems

Low frequency ultrasound (LFUS) was evaluated as a novel disinfection technique within recirculating aquaculture systems both individually and combined with UV-C. Dose-dependent inactivation rates were determined for the total viable counts and model organisms representing different taxa of common fish parasites: the ciliate Paramecium sp., second larval stage (L2) of the nematode Anguillicola crassus and metanauplii of Artemia sp. Application of LFUS up to 19 kJ/L did not reduce the number of colony forming units (CFU), whilst UV-C irradiation was highly effective. Pre-treatment with LFUS reduced the mean size of suspended solids in aquaculture water and thus increased the germicidal effect of UV-C by up to 0.6 log units.LFUS was effective against the eukaryotic organisms, and the dose-dependent inactivation could be well described by functions of an exponential decay. However, the efficiency of LFUS differed greatly between species. A LFUS dose of 1.9 kJ/L (consumed energy) was sufficient to inactivate Artemia by 99%, but a ten times higher dose was necessary to inactivate 95% and 81% of Paramecium and Anguillicola larvae, respectively.In clear water, the energetic efficiency of UV-C (emitted by a low pressure lamp) against Paramecium and Anguillicola larvae was higher compared to LFUS, but LFUS was more efficient against Artemia. However, the efficiency of LFUS against ciliates or nematode larvae would be similar or even higher than UV-C in highly turbid water or if less efficient medium pressure lamps are used. This study shows that LFUS can be applied safely at energy densities that are effective against a wide range of parasites like ciliates, nematodes and crustaceans. The combination of LFUS and UV-C could provide an appropriate water treatment with regards to all relevant pathogens in recirculating aquaculture systems.     

Krill herd: A new bio-inspired optimization algorithm

In this paper, a novel biologically-inspired algorithm, namely krill herd (KH) is proposed for solving optimization tasks. The KH algorithm is based on the simulation of the herding behavior of krill individuals. The minimum distances of each individual krill from food and from highest density of the herd are considered as the objective function for the krill movement. The time-dependent position of the krill individuals is formulated by three main factors: (i) movement induced by the presence of other individuals (ii) foraging activity, and (iii) random diffusion. For more precise modeling of the krill behavior, two adaptive genetic operators are added to the algorithm. The proposed method is verified using several benchmark problems commonly used in the area of optimization. Further, the KH algorithm is compared with eight well-known methods in the literature. The KH algorithm is capable of efficiently solving a wide range of benchmark optimization problems and outperforms the exciting algorithms.     

Preparation,Structural characterization and DNA binding/cleavage affinity of new bioactive nano‐sized metal (II/IV) complexes with oxazon‐Schiff's base ligand

A novel oxazon‐Schiff's base ligand named (E)‐3‐(2‐(4‐(diethylamino)‐2‐hydroxybenzylidene)hydrazineyl)‐2H‐benzo[b][1,4]oxazin‐2‐one (HL) has been synthesized in addition to its nano‐sized divalent and tetravalent Mn (II), Co (II), Ni (II), Cu (II), Zn (II) and Pt (IV) complexes. The structures and geometries of the synthesized compounds have been confirmed using the different analytical and spectroscopic tools such as elemental analysis, uv–vis., IR, HR‐MS, ¹H NMR, ESR, TGA, XRD, EDX, TEM, SEM, AFM, magnetic and molar conductivity measurements. The elemental analyses confirm 1 M: 2 L stoichiometry of the type [PtL₂].2Cl and [ML₂] (M = Mn (II), Co (II), Ni (II), Cu (II) and Zn (II)). The FT‐IR spectral studies illustrated that the ligand bind to the metal ions through the phenolic hydroxy oxygen, azo methine nitrogen carbonyl oxazin oxygen. The spectral tools; UV–Vis, ligand field parameters and ESR in addition to the magnetic moment measurements confirmed octahedral geometry around the metal centres. The absence of coordinated or hydrated water complexes were confirmed by thermal analysis data of the complexes. The electron transfer reactions for the complexes have been studied by cyclic voltammetry. XRD, SEM, TEM, and AFM images confirmed nano‐sized particles and homogeneous distribution over the complex surface. The mode of binding of the complexes with DNA has been performed through electronic absorption titration and viscosity studies. The reaction between the metal complexes and DNA were studied by DNA cleavage. In general, MCF‐7 cell were least sensitive to the tested compounds and all compounds were considerably more toxic to the studied cancer cell lines than to the normal cell line HepG‐2. The binding mode of the compounds and DNA was preferably via intercalation. In addition, these results were confirmed based on theoretical studies . Finally, a linear and exponential correlation between interaction constant (K_b) and IC₅₀ for two human cancer cell was observed.     

Thermochemistry of phosphorus sulfide cages: an extreme challenge for high-level ab initio methods

Structural Chemistry - The enthalpies of formation and isomerization energies of P4Sn molecular cages are not experimentally (or theoretically) well known. We obtain accurate enthalpies of...     

Visible light-excited surface plasmon resonance charge transfer significantly improves the photocatalytic activities of ZnO semiconductor for pollutants degradation

To effectively address environmental pollution, we synthesized Au-loaded ZnO nanocomposites and applied for the photocatalytic degradation of 2-chlorophenol (2-CP) under visible light irradiation. The as-prepared nanophotocatalysts delivered much improved photocatalytic degradation activities as compared to the bare ZnO nanoparticles and 32% of the pollutant was degraded with 2AuZnO in 1 hr. These improved photoactivities are attributed to the extended visible light absorption due to the surface plasmon resonance property of the loaded Au nanoparticles. Moreover, Au nanoparticles played important role in charge separation by inducting excited electrons to the conduction band of ZnO photocatalyst and surface catalysis as confirmed from photoluminescence spectra and amount of the generated hydroxyl radicals. The trapping experiments confirmed that positive holes were the major degrading species during the photocatalytic degradation of 2-CP. This work provides a feasible way to improve the photocatalysis by introducing a proper amount of noble metals over the surface of semiconductor photocatalysts.     

Rapid Synthesis of Block and Cyclic Copolymers via Click Chemistry in the Presence of Copper Nanoparticles

A new method for the rapid and efficient coupling of homopolymers to yield di- and triblock copolymers as well as cyclic polymers using the 3 + 2 π Huisgen copper catalyzed cyclo-addition reaction has been developed. This facile method utilizes commercially available Cu nanoparticles that are tolerant to O(2), easily removable and recyclable.     

Brauhenefloroside E and F; acylated flavonol glycosides from Stocksia brauhica Linn

Two new acylated flavonol glycosides, 3‐O‐{[2‐O‐β‐D ‐glucopyranosyl]‐3‐[O‐β‐D ‐glucopyranosyl]‐4‐[(6‐O‐p‐coumaroyl)‐O‐β‐D ‐glucopyranosyl]}‐α‐L ‐rhamnopyranosyl‐kaempferol 7‐O‐α‐L ‐rhamnopyranoside and 3‐O‐{2‐[(6‐O‐p‐coumaroyl)‐O‐β‐D ‐glucopyranosyl]‐3‐[O‐β‐D ‐glucopyranosyl]‐4‐[(6‐O‐p‐coumaroyl)‐O‐β‐D ‐glucopyranosyl]}‐α‐L ‐rhamnopyranosyl‐kaempferol 7‐O‐α‐L ‐rhamnopyranoside, trivially named as brauhenefloroside E (1) and F (2), respectively, were isolated from the fruits of Stocksia brauhica and their structures were elucidated using spectroscopic methods, including 2D NMR experiments. Copyright © 2010 John Wiley & Sons, Ltd.     

An alternative proof of a characterization of Cohen-Macaulay bipartite graphs

Recently, Herzog and Hibi explicitly described all Cohen-Macaulay bipartite graphs by using the Stanley-Reisner ideal of the Alexander dual of the simplicial complex Δ _P associated to a finite poset P. In this paper, we will present a short proof that does not use the Stanley-Reisner ideal of the Alexander dual of Δ _P .