A microelectrochemical sensing system for the determination of Epstein–Barr virus antibodies

An electrochemical method for the detection of Epstein–Barr virus (EBV) infections is described. The method relies on an immunoassay with electrochemical read-outs based on recombinant antigens. The antigens are immobilised on an Au electrode surface and used to complementarily bind antibodies from serum samples found during different stages of infection with EBV. Thiol chemistry under formation of self-assembled monolayers functions as a means to immobilise the antigens at the Au electrodes. A reporter system consisting of a secondary antibody labelled with alkaline phosphatase is used for electrochemical detection. The feasibility of the assay design is demonstrated and the assay performance is tested against the current gold standard in EBV detection. Close correlation is obtained for the results found for the developed electrochemical immunoassay and a standard line assay. Moreover, the electrochemical immunoassay is combined with a nanoporous electrode system allowing signal amplification by means of redox recycling. An amplification factor of 24 could be achieved.     

Two new 1-D and 3-D Wells–Dawson structures assisted by alkali metals

Two new Wells–Dawson based compounds containing alkali metals, [Ag(H₂biim)₂]₂·[Ag₅(H₂biim)₁₀Na₂(H₂O)₂(H_3/2P₂W₁₈O₆₂)₂]·12H₂O (1) and [Cd(H₂biim)₂?K(P₂W₁₈O₆₂)_1/2] (2) (H₂biim?=?2,2′-biimidazole), have been synthesized under hydrothermal conditions. In 1, two-supporting Wells–Dawson anions are linked by a [Ag(H₂biim)₂]⁺ subunit to form a dimer. The adjacent dimers are further connected by Na⁺ through (POM)O-Na-O(POM) bonds to build a 1-D chain. In 2, adjacent anions are linked by two [Cd₂(H₂biim)₂]⁴⁺ subunits and a 1-D chain is formed. Furthermore, the anion in the chain is fused by six K⁺ ions and a 3-D framework is obtained. The alkali metals exhibit crucial influence on the conversion of dimensionality assisting anions and Ag-H₂biim subunits to construct 1-D and 3-D frameworks. The electrochemical and photocatalytic properties of 1 and 2 have been investigated.     

Underpinning energetics of lithium bonding and stability in the Li–Pt–Sn system

Within the Li–Pt–Sn system, we examine the electronic structures and Li-binding of LiPtSn₂, Li₂PtSn and Li₃Pt₂Sn₃ with fluorite-related crystal structures. The structures with totally de-intercalated lithium keep the characteristics of the pristine ternary compound with a reduction of the volume. In Li₃Pt₂Sn₃ the binding energies of lithium belonging to three crystallographically inequivalent Wyckoff sites are different and point to distinct activities of de-intercalation concomitant with site-selective bonding magnitudes. The derived potentials are within the range of non-oxide binary and ternary lithium based compounds and indicate the possibility of at least partial delithiation.     

Crystal structures,site occupations and phase equilibria in the system V–Zr–Ge

The V–Zr–Ge system was studied for two isothermal sections at 900 and 1200 °C. Three ternary compounds VZrGe (tI12, I4/mmm, CeScSi-type), V_xZr_5?xGe₄ (oP36, Pnma, Sm₅Ge₄-type) and V_4+xZr_2?xGe₅ (oI44, Ibam, Si₅V₆-type) were structurally characterized. Optical microscopy and powder X-ray diffraction (XRD) were used for initial sample characterization and electron probe microanalysis (EPMA) of the annealed samples was used to determine the exact phase compositions. The variation of the cell parameters of the various ternary solid solutions with the composition was determined. The three ternary phases were structurally characterized by means of single crystal and powder XRD. While VZrGe is almost a line compound, V_xZr_5?xGe₄ (0.2 ≤ x ≤ 3.0) and V_4+xZr_2?xGe₅ (0.06 ≤ x ≤ 1.2) are forming extended solid solution ranges stabilized by differential fractional site occupancy of V and Zr on the metal sites.     

Energetics, structures, bonding, and kinetics of the HSCl–HClS system

The [H,S,Cl] potential-energy surface has been investigated at the self-consistent field (SCF), complete active space self-consistent field (CASSCF), second-order M?ller–Plesset, coupled-cluster single-double and perturbative triple excitation, [CCSD(T)]/6-31G(d,p), 6-31G(2df,2pd), and correlation-consistent polarized valence triple zeta (cc-pVTZ) levels of theory. CCSD(T)/ cc-pVTZ results predict a very stable HSCl species, an isomer HClS, 51.84 kcal/mol higher in energy, and a transition state 57.68 kcal/mol above HSCl. Independent of the level of theory, results with the smaller 6-31G(d,p) basis set turned out to be poor, especially for HClS. Vibrational analysis indicates that both species can be easily differentiated if isolated. Bonding differences between these molecules are illustrated by contour plots of valence orbitals. Viewed classically, bonding in HClS involves a dative bond. Transition-state rate constants, and equilibrium constants for the HSCl ↔ HClS isomerization have been estimated for various temperatures (200–1000 K). At 298.15 K, the forward rate is predicted to be 7.95 × 10⁻²⁹ s⁻¹, and the equilibrium constant to be 2.31 × 10⁻³⁸. Tunneling corrections vary from 1.57 at 298.15 K to 1.05 at 1000 K. Activation energies have been obtained by a two-points linear fit to the Arrhenius equation. Received: 7 May 1999 / Accepted: 22 July 1999 / Published online: 4 October 1999     

Vapor–liquid equilibria for the system 1-propanol+n-hexane near the critical region

Vapor–liquid equilibria and critical point data for the system 1-propanol+n-hexane at 483.15, 493.15, 503.15 and 513.15 K are reported. The critical pressures determined from the critical opalescence of the mixture were compared with published data for the system 2-propanol+n-hexane. Phase behavior measurements were made in a modified circulating type apparatus with a view cell. These mixtures are highly nonideal because of the hydrogen bonding of 1-propanol. Modeling of the experimental data has been performed using the multi-fluid nonrandom lattice fluid with hydrogen-bonding (MF-NLF-HB) equation of state and the Peng–Robinson–Stryjek–Vera (PRSV) equation of state with Wong–Sandler mixing rule. The critical points and the critical locus were also calculated.     

Sensitivity and stability of the Fricke–gelatin–xylenol orange gel dosimeter

Spectrophotometric measurements of the Fricke–gelatin–xylenol orange (FGX) gel dosimeter demonstrated reproducible linear dose response up to 25 Gy. However, oxidation processes continue post-irradiation, affecting the response of this dosimetry system. Additional oxygenation during preparation increases the sensitivity of the gel but does not improve the auto-oxidation stability of the dosimeter post-irradiation. A suitably stable gel composition that is recommended for radiotherapy dosimetry measurements contains 0.5 mM ferrous ammonium sulphate, 50 mM sulphuric acid, 0.15 mM xylenol orange and 3.0% by weight gelatin.     

Thermodynamic stability of solid phases in the system Cu–O–Al2O3 by means of the EMF and DSC-TGA techniques

Journal of Solid State Electrochemistry - Thermodynamic properties of solid phases in the Cu–O–Al2O3 system were measured by means of the EMF method with oxygen concentration galvanic...     

Mechanochemical synthesis and thermal stability of phases in the Y2O3–Yb2O3 system

Substitutional, continuous solid solution of the general formula Y_2–xYb_xO₃ was obtained from the mixture of Y₂O₃ and Yb₂O₃ oxides, for the first time by the mechanochemical method in a high-energy ball milling. The monophasic samples of nanocrystalline solid solution for x?>?0.00 and x?<?2.00 were examined by the methods: XRD, DTA, SEM, IR and UV–Vis–DR. As follows from the results, the solid solution crystallizes in cubic system and is isostructural with Y₂O₃ and Yb₂O₃. The solution is stable in the air atmosphere up to at least 900°C, and its decomposition temperature decreases with the increase in x, that is, with decreasing number of Yb³⁺ ions replacing Y³⁺ ions in the crystal lattice of Y₂O₃. The energy band gap estimated for the solid solution varies from?~?5.30 eV for x?=?0.50 to?~?4.90 eV for x?=?1.50, which means that it is an insulator.

     

Two spin systems based on [Ni(dmit)2]− building blocks exhibiting 1-D chain and 2-D sheet structures: crystal structures and magnetic properties

The crystal structures and magnetic properties for two ion-pair complexes, [MG][Ni(dmit)₂] (1) and [RhB][Ni(dmit)₂] (2) (MG⁺ = N-(4-((4-(dimethylamino)phenyl)(phenyl)methylene)cyclohexa-2,5-dienylidene)-N-methylmethanaminium, RhB⁺ = 9-(2-carboxyphenyl)-3,6-bis(diethylamino)xanthylium; dmit^2? = 1,3-dithiole-2-thione-4,5-dithiolate), have been investigated. Complex 1 crystallizes in the monoclinic space group P2₁/c, the stacking interactions between the GM⁺ and [Ni(dmit)₂]^? lead to the anion exhibiting a banana-shaped molecular geometry; the neighboring anions form a 1-D alternating chain along the crystallographic [1 1 0] direction via intermolecular lateral-to-lateral and head-to-head S ··· S contacts. The temperature dependence of magnetic susceptibility from 2–350 K does not display the magnetic character of a 1-D chain; the magnetic susceptibility data were fit to the Curie–Weiss equation to give C = 0.351(15) emu K mol^?1, θ = ?3.51(28) K, and χ ₀ = 8.00(3) × 10^?5 emu mol^?1. Complex 2 belongs to the triclinic space group P-1 with two crystallographic inequivalent [Ni(dmit)₂]^? anions, which exhibit perfect planar geometry. Two ethyl groups of RhB⁺ are disordered over two positions at 296 K, and one becomes ordered at 150 K. The [Ni(dmit)₂]^? anions form a 2-D molecular layer via intermolecular lateral-to-lateral and head-to-lateral S ··· S interactions with the anionic layer parallel to the crystallographic (0 1 ?1) plane. The temperature variation of magnetic susceptibility from 2 to 350 K shows that antiferromagnetic coupling dominates in the anionic layer, and the disorder–order changes of cationic structure are not coupled to magnetic property.     

Genomic assays for Epstein–Barr virus-positive gastric adenocarcinoma

A small set of gastric adenocarcinomas (9%) harbor Epstein–Barr virus (EBV) DNA within malignant cells, and the virus is not an innocent bystander but rather is intimately linked to pathogenesis and tumor maintenance. Evidence comes from unique genomic features of host DNA, mRNA, microRNA and CpG methylation profiles as revealed by recent comprehensive genomic analysis by The Cancer Genome Atlas Network. Their data show that gastric cancer is not one disease but rather comprises four major classes: EBV-positive, microsatellite instability (MSI), genomically stable and chromosome instability. The EBV-positive class has even more marked CpG methylation than does the MSI class, and viral cancers have a unique pattern of methylation linked to the downregulation of CDKN2A (p16) but not MLH1. EBV-positive cancers often have mutated PIK3CA and ARID1A and an amplified 9p24.1 locus linked to overexpression of JAK2, CD274 (PD-L1) and PDCD1LG2 (PD-L2). Multiple noncoding viral RNAs are highly expressed. Patients who fail standard therapy may qualify for enrollment in clinical trials targeting cancer-related human gene pathways or promoting destruction of infected cells through lytic induction of EBV genes. Genomic tests such as the GastroGenus Gastric Cancer Classifier are available to identify actionable variants in formalin-fixed cancer tissue of affected patients.     

Application of isothermal calorimetry and thermal analysis for the investigation of calcined gypsum–lime–metakaolin–water system

Journal of Thermal Analysis and Calorimetry - The calcined gypsum–lime–metakaolin–water system and its subsystems consisting of two and three components are analyzed using the...     

Structural and spectroscopic investigations of the Eu–CDTA system

Two crystal structures of Eu^III complexes with CDTA (trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetate), [C(NH₂)₃]₃[Eu₂(CDTA)₂(H₂O)₂]ClO₄ · 7H₂O (I) and [C(NH₂)₃][Eu(CDTA)(H₂O)] · 2.375H₂O (II), are presented. Both structures are polymeric and the central metal ions are eight-coordinate. The first coordination sphere of each Eu^III cation contains five carboxylate oxygen atoms, two nitrogen ones and a water molecule. For I, as well as for water solutions of the Eu^III–CDTA complex at various pH values, the spectroscopic (UV–Vis) properties were investigated.     

From 2-D layer to 2-D → 3-D parallel interpenetration: syntheses,structures and luminescent properties

Two new coordination polymers based on 1,1′-(1,4-butanediyl)bis(imidazole) (bbi) and 5-hydroxyisophthalic acid (OH-BDC), [Co₂(HO-BDC)₂(bbi)₂]·H₂O (1) and [Zn(HO-BDC)(bbi)] (2), have been hydrothermally synthesized. The complexes were characterized by single-crystal X-ray diffraction, IR, and elemental analysis. The structure determination reveals that 1 manifests a deeply corrugated 2-D layer with a (4,4) lattice. For 2, there is a highly undulating 2-D (4,4) layer structure. The layers penetrate by each other to give a 2-D → 3-D parallel interpenetrating network. Fluorescence properties and thermal stabilities of 1 and 2 in the solid state have been studied.     

Analysis of the hyperfine structures and

From the theories of the nuclear hyperfine structure (HFS) and Λ doubling of diatomic molecules, several brief algebraic equations for interpretation of HFS and Λ doubling of transitions of diatomic molecule have been developed. A few important parameters of HFS and Λ doubling of¹⁵N¹⁶O have been efficiently and accurately obtained from the analysis of the high resolution spectra of¹⁵N¹⁶O (X²∏) observed in our experiments with these equations. This method can provide an effective approach to obtain important hyperfine parameters of novel radicals from their high resolution laser magnetic resonance spectra. Liu Yu-yan, Guo Yuan-qing, Assignments of FIR-LMR spectra of CF X²∏(υ= 1) and MIR-LMR spectra of NO X²∏ (υ =1←0), Spectroscopy and Spectral Analysis (in press).     

Influence of gelator structures on formation and stability of supramolecular hydrogels

A supramolecular hydrogel(defined as G1) formed from 1,2,4,5-benzene tetracarboxylic acid (BTCA) and 2-amino-3- hydroxypyridine possessed higher T_(gel) than that of another hydrogel(defined as G2) formed from BTCA and 3-hydroxypyridine. Based on the analysis of their xerogels by ~1H NMR,IR and XRD,the higher stability of G1 was attributed to the formation of stronger hydrogen binding enhanced by the ortho amino group of 2-amino-3-hydroxypyridine.     

“Increased-valence” structures and the bonding for some cyclic sulphur-nitrogen compounds

For the following (mostly cyclic) thiazyl compounds, attention is given to the construction and examination of “increased-valence” structures when sulphur 3d-orbitals are omitted from the bonding schemes: S₄N₄ and its adducts, Ar₂S₄N₃⁺, S₄N₃⁺, S₄N₄O₂, S₄N₄²⁺, S₅N₅⁺, S₄N₅⁻, S₄N₅O⁻, S₅N₆, S₃N₂⁺, S₆N₄²⁺, and S₃N₂X (with X  Cl⁺, NSO₂F, NCOCF₃, and NP₃N₃F₅). Lewis-Langmuir octet structures are written down, and then some of the non-bonding electrons for these structures are delocalized into bonding SN orbitals. The resulting “increased-valence” structures have one-electron-bonds and fractional electron-pair bonds, as well as normal electron-pair bonds. The hypothesis that fractional electron-pair bonds are shorter than one-electron bonds leads to deductions concerning the relative lengths of the SN bonds that are mostly in general agreement with the experimental values.The nearest-neighbour SS bonds for each of S₄N₄, S₄N₅⁻, S₅N₆ S₄N₃⁺, S₃N₂⁺ and derivatives, and S₆N₄²⁺ are longer than the standard SS single-bond length of ∼ 2.06Å. These lengthenings are due either to less-than-unity values for the SS σ-bond numbers in the “increased-valence” structures, or to the straining of the SS σ-bonds as a consequence of local planarity requirements.The results of simple Hückel molecular orbital calculations of bond lengths are also reported for some of the planar systems. The calculations support the hypothesis that expanded valence-shell linkages (such as

and

for 2-and 3-coordinate sulphur) are not required in the valence structures for the systems considered in this paper.