Simultaneous detection of five different 2-hydroxyethyl-DNA adducts formed by ethylene oxide exposure, using a high-performance liquid chromatography/electrospray ionisation tandem mass spectrometry assay

A method has been developed for the simultaneous detection and quantitation of five different 2-hydroxyethyl-DNA (HE-DNA) adducts that could be formed as a result of exposure to ethylene oxide (EO). In addition to the major N7-HE-guanine (N7-HEG) adducts this assay can also measure the less prevalent but potentially more biologically significant N1-HE-2'-deoxyadenosine (N1-HEdA), O(6)-HE-2'-deoxyguanosine (O(6)-HEdG), N(6)-HE-2'-deoxyadenosine (N(6)-HEdA) and N3-HE-2'-deoxyuridine adducts (N3-HEdU). The method involves the isolation of HE adducts from the unmodified nucleosides by either neutral thermal hydrolysis or enzymatic digestion, followed by high-performance liquid chromatographic (HPLC) purification, before detection and quantification by liquid chromatography tandem mass spectrometry (LC/MS/MS) using selective reaction monitoring (SRM). The limits of detection were in the range 0.5-25 fmol for each individual adduct, making this one of the most sensitive assays available for the detection of N7-HEG. To illustrate the possible applications of the assay, it has been employed in the measurement of endogenous/background and EO-induced HE adducts in a variety of DNA samples.     

Fingerprinting of human bile during liver transplantation by capillary electrophoresis

Increasing rates of success in liver transplantation have increased the number of cases considered. However, liver post-transplant graft dysfunction of liver transplants (TXs) is not fully understood and by applying holistic approaches we can investigate metabolic change deriving from confounding factors such as liver fat content, ischaemia time, donor age, recipient's health, etc. Twenty-six hepatic bile samples taken from liver donors and recipients were retrieved from a total of six TXs, from these one recipient underwent post-graft dysfunction. CE was employed to fingerprint bile collected at 10 min increments in the donors and in the recipients. The electropherograms of these samples were aligned and normalised using correlation optimised warping algorithms and modelled with multivariate techniques. The resulting metabolic signatures were compared; in general donors and recipients showed distinct fingerprints and clustered separately. When a partial least square discriminant analysis (PLS-DA) model was constructed between donor and recipient's samples, a recipient of a 32 year old liver with normal steatosis, and shortest cold ischaemia time showed as the observation nearest to its donor observation, denoting minimal metabolic change. This study proposes CE fingerprinting of human bile as a promising technique to help unravel the complex metabolic pathways involved during transplantation.     

In situ hydrothermal growth of a zirconium-based porphyrinic metal-organic framework on stainless steel fibers for solid-phase microextraction of nitrated polycyclic aromatic hydrocarbons

Microchimica Acta - The authors describe the in-situ hydrothermal growth of a porphyrinic zirconium metal-organic framework (MOF), referred to as PCN-222(Zr), on stainless steel fibers. The...     

New C19-diterpenoid alkaloids from the parent roots of Aconitum carmichaelii

Aconitum carmichaelii is a widely used traditional Chinese medicine and important source of clinical drugs. The parent roots of A. carmichaelii were investigated resulting in the isolation and identification of five new C₁₉-diterpenoid alkaloids; 14α-benzoyloxy-N-ethyl-15α-hydroxy-1α,6α,8β,16β,18-pentamethoxyaconitane formate (1), 14α-benzoyloxy-8β-butoxy-N-ethyl-13β,15α-dihydroxy-1α,6α,16β,18-tetramethoxyaconitane formate (2), 14α-benzoyloxy-8β-butoxy-N-ethyl-3α,13β,15α-trihydroxy-1α,6α,16β,18-tetramethoxylaconitane (3), 14α-benzoyloxy-8β-butoxy-3α,13β,15α-trihydroxy-1α,6α,16β,18-tetramethoxyl-N-methylaconitane (4) and 8β,14α-dibenzoyloxy-N-ethyl-13β,15α-dihydroxy-1α,6α,16β,18-tetramethoxyaconitane (5).     

Non-linear plasmon response to protein binding at a nanostructured gold particle plasmon resonance surface

Rapid adsorption kinetics have been observed for protein binding to a 800 nm aggregated nanoparticle, showing extreme sensitivity resulting from a non-linear particle plasmon response.     

Vanishing viscosity in the plane for vorticity in borderline spaces of Besov type

The existence and uniqueness of solutions to the Euler equations for initial vorticity in BΓ∩Lp₀∩Lp₁ was proved by Misha Vishik, where BΓ is a borderline Besov space parameterized by the function Γ and 1<p₀<2<p₁. Vishik established short time existence and uniqueness when Γ(n)=O(logn) and global existence and uniqueness when . For initial vorticity in BΓ∩L², we establish the vanishing viscosity limit in L²(R²) of solutions of the Navier-Stokes equations to a solution of the Euler equations in the plane, convergence being uniform over short time when Γ(n)=O(logn) and uniform over any finite time when Γ(n)=O(logκn), 0?κ<1, and we give a bound on the rate of convergence. This allows us to extend the class of initial vorticities for which both global existence and uniqueness of solutions to the Euler equations can be established to include BΓ∩L² when Γ(n)=O(logκn) for 0<κ<1.     

Unexpected Self‐Sorting Self‐Assembly Formation of a [4:4] Sulfate:Ligand Cage from a Preorganized Tripodal Urea Ligand

The design and synthesis of tripodal ligands 1 – 3 based upon the N‐methyl‐1,3,5‐benzenetricarboxamide platform appended with three aryl urea arms is reported. This ligand platform gives rise to highly preorganized structures and is ideally suited for binding SO₄^2? and H₂PO₄^? ions through multiple hydrogen‐bonding interactions. The solid‐state crystal structures of 1 – 3 with SO₄^2? show the encapsulation of a single anion within a cage structure, whereas the crystal structure of 1 with H₂PO₄^? showed that two anions are encapsulated. We further demonstrate that ligand 4 , based on the same platform but consisting of two bis‐urea moieties and a single ammonium moiety, also recognizes SO₄^2? to form a self‐assembled capsule with [4:4] SO₄^2?: 4 stoichiometry in which the anions are clustered within a cavity formed by the four ligands. This is the first example of a self‐sorting self‐assembled capsule where four tetrahedrally arranged SO₄^2? ions are embedded within a hydrophobic cavity.     

Identifying Different Types of Catalysts for CO2 Reduction by Ethane through Dry Reforming and Oxidative Dehydrogenation

The recent shale gas boom combined with the requirement to reduce atmospheric CO₂ have created an opportunity for using both raw materials (shale gas and CO₂) in a single process. Shale gas is primarily made up of methane, but ethane comprises about 10 % and reserves are underutilized. Two routes have been investigated by combining ethane decomposition with CO₂ reduction to produce products of higher value. The first reaction is ethane dry reforming which produces synthesis gas (CO+H₂). The second route is oxidative dehydrogenation which produces ethylene using CO₂ as a soft oxidant. The results of this study indicate that the Pt/CeO₂ catalyst shows promise for the production of synthesis gas, while Mo₂C‐based materials preserve the C? C bond of ethane to produce ethylene. These findings are supported by density functional theory (DFT) calculations and X‐ray absorption near‐edge spectroscopy (XANES) characterization of the catalysts under in situ reaction conditions.