In-field monitoring of cleaning efficiency in waste water treatment plants using two phenol-sensitive biosensors

Two amperometric biosensors based on the enzymes cellobiose dehydrogenase (CDH) and quinoprotein-dependent glucose dehydrogenase (GDH), have been applied for monitoring the phenolic content in water samples, collected at different stages of a waste water treatment process, thus representing different cleaning levels of two waste water treatment plants (WWTPs). The biosensor measurements were performed in-field, compared with the results obtained by liquid chromatography-mass spectrometry and were further correlated with the cleaning efficiencies of the WWTPs. The effect of several potentially interfering compounds on the sensor response was also studied.The general purpose of the study was to evaluate the potential use of biosensors, not as quantitative tools for phenol analysis, but rather as screening tools indicating a certain trend, i.e. compounds present or not present, and potential correlation with sample toxicity. It was found that the biosensors and LC-MS results were not quantitatively comparable, however, both sensors could follow the decrease of the phenol content from the influent, primary treated and effluent waters. In addition, the correlation between biosensor inhibition and sample toxicity is discussed.     

Synthesis and structural characterisation of group 10 metal(II) gallyl complexes: analogies with platinum diboration catalysts?

Reactions of the anionic gallium(i) heterocycle, [:Ga{[N(Ar)C(H)](2)}](-) (Ar = C(6)H(3)Pr(i)(2)-2,6), with a variety of mono- and bidentate phosphine, tmeda and 1,5-cyclooctadiene (COD) complexes of group 10 metal dichlorides are reported. In most cases, salt elimination occurs, affording either mono(gallyl) complexes, trans-[MCl{Ga{[N(Ar)C(H)](2)}}(PEt(3))(2)] (M = Ni or Pd) and cis-[PtCl{Ga{[N(Ar)C(H)](2)}}(L)] (L = R(2)PCH(2)CH(2)PR(2), R = Ph (dppe) or cyclohexyl (dcpe)), or bis(gallyl) complexes, trans-[M{Ga{[N(Ar)C(H)](2)}}(2)(PEt(3))(2)] (M = Ni, Pd or Pt), cis-[Pt{Ga{[N(Ar)C(H)](2)}}(2)(PEt(3))(2)], cis-[M{Ga{[N(Ar)C(H)](2)}}(2)(L)] (M = Ni, Pd or Pt; L = dppe, Ph(2)CH(2)PPh(2) (dppm), tmeda or COD). The crystallographic and spectroscopic data for the complexes show that the trans-influence of the gallium(i) heterocycle lies in the series, B(OR)(2) > H(-) > PR(3) approximately [:Ga{[N(Ar)C(H)](2)}](-) > Cl(-). Comparisons between the reactivity of one complex, [Pt{Ga{[N(Ar)C(H)](2)}}(2)(dppe)], with that of closely related platinum bis(boryl) complexes indicate that the gallyl complex is not effective for the catalytic or stoichiometric gallylation of alkenes or alkynes. The phosphaalkyne, Bu(t)C[triple bond, length as m-dash]P, does, however, insert into one gallyl ligand of the complex, leading to the novel, crystallographically characterised P,N-gallyl complex, [Pt{Ga{[N(Ar)C(H)](2)}}{Ga{PC(Bu(t))C(H)[N(Ar)]C(H)N(Ar)}}(dppe)]. An investigation into the mechanism of this insertion reaction has been undertaken.     

The zeta potential of surface-functionalized metallic nanorod particles in aqueous solution

Metallic nanoparticles suspended in aqueous solutions and functionalized with chemical and biological surface coatings are important elements in basic and applied nanoscience research. Many applications require an understanding of the electrokinetic or colloidal properties of such particles. We describe the results of experiments to measure the zeta potential of metallic nanorod particles in aqueous saline solutions, including the effects of pH, ionic strength, metallic composition, and surface functionalization state. Particle substrates tested include gold, silver, and palladium monometallic particles as well as gold/silver bimetallic particles. Surface functionalization conditions included 11-mercaptoundecanoic acid (MUA), mercaptoethanol (ME), and mercaptoethanesulfonic acid (MESA) self-assembled monolayers (SAMs), as well as MUA layers subsequently derivatized with proteins. For comparison, we present zeta potential data for typical charge-stabilized polystyrene particles. We compare experimental zeta potential data with theoretically predicted values for SAM-coated and bimetallic particles. The results of these studies are useful in predicting and controlling the aggregation, adhesion, and transport of functionalized metallic nanoparticles within microfluidic devices and other systems.     

Identification of thermal material parameters for thermo-mechanically coupled material models

Meccanica - The possibility of accurately identifying thermal material parameters on the basis of a simple tension test is presented, using a parameter identification framework for...     

Elementary equivalence for lattices of subalgebras of free algebras

A class of varieties V (including all finitely based lattice varieties) is determined for which the elementary equivalence of lattices of subalgebras of free V-algebras, F_v(X) and F_v(Y), is equivalent to sets X and Y being second-order equivalent. Supported by RFFR grant No. 99-01-00571. Supported by the National Research Foundation of the Republic of South Africa, and by the University of Cape Town Research Committee. Translated fromAlgebra i Logika, Vol. 39, No. 5, pp. 595–601, September–October, 2000.     

A Target Recycling Amplification Process for the Digital Detection of Exosomal MicroRNAs through Photonic Resonator Absorption Microscopy

Exosomal microRNAs (miRNAs) have considerable potential as pivotal biomarkers to monitor cancer development, dis-ease progression, treatment effects and prognosis. Here, we report an efficient target recycling amplification process (TRAP) for the digital detection of miRNAs using photonic resonator absorption microscopy. We achieve multiplex digital detection with sub-attomolar sensitivity in 20 minutes, robust selectivity for single nucleotide variants, and a broad dynamic range from 1 aM to 1 pM. Compared with traditional qRT-PCR, TRAP showed similar accuracy in profiling exosomal miRNAs derived from cancer cells, but also exhibited at least 31-fold and 61-fold enhancement in the limits of miRNA-375 and miRNA-21 detection, respectively. The TRAP approach is ideal for exosomal or circulating miRNA biomarker quantification, where the miRNAs are present in low concentrations or sample volume, with potentials for frequent, low-cost, and minimally invasive point-of-care testing.     

Environmental Effects on Cellular Photosensitization: Correlation of Phototoxicity Mechanism with Transient Absorption Spectroscopy Measurements

Abstract— Little is directly known about the influence of the local environment experienced by a photosensitizer in a biological system on its photophysics and photochemistry. In this paper, we have addressed this issue by correlating mechanistic studies using laser flash photolysis with cellular phototoxicity data, obtained under the same experimental conditions. In particular, we have focused on the interaction between local concentrations of photosensitizer (deuteroporphyrin) and oxygen in determining the mechanism of phototoxicity in L1210 cells. In cells, as well as in models such as liposomes and red blood cell ghosts, hypochromicity and a reduction in fluorescence and intersystem crossing yields are observed on increasing the photosensitizer concentration between 0.5 and 20 μM, which illustrates the onset of a self-association. In aerated cellular preparations, the phototoxicity is predominantly type II (singlet oxygen) for all concentrations studied but an oxygen-independent mechanism occurs at the higher concentrations in deaerated samples. These observations are readily explained by consideration of triplet state kinetics as a function of oxygen and photosensitizer concentrations in cells. The rate constant for quenching of the photosensitizer triplet state by oxygen in cells was measured as 6.6 × 10⁸ M^?1 s^?1 and by photosensitizer ground state as -10⁶M^?1s^?1 (in terms of local concentration). The latter reaction gave rise to a long-lived species that is presumably responsible for the oxygen-independent phototoxicity observed at the higher photosensitizer concentrations used. This self-quenching of the triplet state is postulated to arise from electron transfer resulting in radical ion formation. Under conditions where no self-quenching contributes, the phototoxicity measured as a function of oxygen concentration correlates well with a model based on the determined kinetic parameters, thus, unambiguously proving the intermediacy of singlet oxygen. These effects should be borne in mind when interpreting phototoxicity mechanisms from in vitro cell studies. The excellent correlation achieved between laser flash photolysis data and measured phototoxicity gives credence to the direct use of photophysical techniques to elucidate photochemical mechanisms in biological media.     

Hydrogenation of

The course of the hydrogenation of [5]- and [6]metacyclophane (1b and 1c) and their thermochemistry is described. Both compounds are hydrogenated rapidly (within 10 s) to furnish the bridgehead olefins 13b and 12c. The accompanying hydrogenation enthalpies are -220 and -141 kJmol(-1), respectively. Strain energies (SE) and olefinic strains (OS) of a number of bridgehead olefins have been evaluated by DFT calculations; it was concluded that 13b belongs to the class of hyperstable olefins which correlates nicely with its reluctance to undergo hydrogenation. By combining experimental hydrogenation enthalpies and DFT calculations, SE of 187 and 121 kJmol(-1) were derived for 1b and 1c.     

Physico-chemical study of fouling mechanisms of ultrafiltration membrane on Biwa lake (Japan)

Many studies have been undertaken to understand the fouling of the ultrafiltration membranes in drinking water treatment. Physico-chemical fouling of membranes depends on characteristics of the raw water and membrane surface properties. In the case of Biwa lake, some chemical parameters as Si and Fe concentrations change with temperature (season) causing irreversible fouling. While some exits on the influence of the particle mineralogy on the fouling, little work has been developed to elucidate the relation between the physicochemical complexity of the cake and the fouling. Generally clays or oxides are known to lead to a reversible fouling. In this work, the interactions between a UF organic membrane with minerals leading to a hardly reversible fouling are studied. In the case of the Biwa lake water, fouling of ultrafiltration membranes results from the formation of a Si-rich ferric gel directly deposited on the membrane surface and a secondary allophanic gel layer at a bigger distance. The deposit nature and the membrane/cake interactions were studied using infra-red, X-ray diffraction, Al and Si NMR and EXAFS technics. The effect of mineral particles, especially ferric oxides associated with silica, has been demonstrated. The formation of Fe---Si gel directly on the membrane surface is mainly responsible for the fouling. The change of these particles is less negative than the membrane surface. The structure of such a material is complex. The low permeability of the gel is at the prime origin of the fouling.     

Hybrid graphene and graphitic carbon nitride nanocomposite: gap opening, electron-hole puddle, interfacial charge transfer, and enhanced visible light response

Opening up a band gap and finding a suitable substrate material are two big challenges for building graphene-based nanodevices. Using state-of-the-art hybrid density functional theory incorporating long-range dispersion corrections, we investigate the interface between optically active graphitic carbon nitride (g-C(3)N(4)) and electronically active graphene. We find an inhomogeneous planar substrate (g-C(3)N(4)) promotes electron-rich and hole-rich regions, i.e., forming a well-defined electron-hole puddle, on the supported graphene layer. The composite displays significant charge transfer from graphene to the g-C(3)N(4) substrate, which alters the electronic properties of both components. In particular, the strong electronic coupling at the graphene/g-C(3)N(4) interface opens a 70 meV gap in g-C(3)N(4)-supported graphene, a feature that can potentially allow overcoming the graphene's band gap hurdle in constructing field effect transistors. Additionally, the 2-D planar structure of g-C(3)N(4) is free of dangling bonds, providing an ideal substrate for graphene to sit on. Furthermore, when compared to a pure g-C(3)N(4) monolayer, the hybrid graphene/g-C(3)N(4) complex displays an enhanced optical absorption in the visible region, a promising feature for novel photovoltaic and photocatalytic applications.