An immunosensor for syphilis

An immuno responsive membrane was prepared by immobilizing Wasserman antigen to acetylcellulose. The antigen-binding membrane was used in developing an immunosensor for determining specifically corresponding antibody in serum. The senor is characterized by electrochemical determination of the antigen-antibody complex formed at the membranesoluti on interface. Experimental data on the applicability of the sensor to serology tests for syphilis are given as well as an outline of a possible mechanism for evaluating the electrical potential difference across the antigen-binding membrane.     

Molecular aggregation of solid aromatic polymers. III. Small-angle X-ray scattering from aromatic polyamideimide film

Molecular aggregation in polytrimellitamideimide (PAI) was investigated by small-angle x-ray scattering (SAXS). PAI films annealed above the glass transition temperature show a scattering peak characteristic of two-phase structure. A one-dimensional model was used to analyze these SAXS curves. The more ordered phases are produced at higher annealing temperature. The average thickness of the ordered lamellae is comparable with the repeating length of the main chain. The relative difference of electron density between two phases is only a few percent, which shows that the two-phase structure of PAI, like that of aromatic polyimide, differs essentially from that of ordinary crystalline polymers.     

EHF theory of chemical reactions V. Nature of manganese–oxygen bonds by hybrid density functional theory (DFT) and coupled‐cluster (CC) methods

Hybrid density functional theory (DFT) and post‐Hartree–Fock methods are compared by depicting potential energy curves of the O–O dissociation of hydroperoxide and the M–O dissociation of transition‐metal oxides. The former approach includes BLYP, B2LYP, B3LYP, and more general hybrid DFT methods, while the unrestricted Hartree–Fock (UHF) coulpled‐cluster (UCC) SD(T) method is considered as the latter approach. The hybrid DFT methods can reproduce the potential curve of the O–O dissociation process and the dissociation energy of HOOH by UCCSD(T). The methods are also useful for depicting potential curves of copper oxide (CuO) and manganese oxide (MnO), and reproduce the experimental M–O binding energies. The nature of Mn–O bonds in the naked Mn–O, Mn–O porphyrine system and model complexes, XH₃Mn(IV)O₂Mn(IV)H₃Y (X,Y=O,H), are examined in relation to the possible mechanisms of oxygenation reactions. It is found that the radical character of Mn–O bonds increases with the increase of the oxidation number of the Mn ion in these systems. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001     

Improvement of thermoplasticity for s‐BPDA/PDA by copolymerization and blend with novel asymmetric BPDA‐based polyimides

Asymmetric biphenyl type polyimides (PI) derived from 2,3,3′,4′‐biphenyltetracarboxylic dianhydride (a‐BPDA) and p‐phenylenediamine (PDA) or 4,4′‐oxydianiline (ODA) show higher T_gs, and much better thermoplasticity than the corresponding isomeric PIs from symmetric 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (s‐BPDA). In addition, a‐BPDA‐derived PIs are completely amorphous owing to their bent chain structures and highly distorted conformations, whereas the PIs from s‐BPDA are semicrystalline. a‐BPDA‐derived PIs possessing these properties or the a‐BPDA monomer were used as a flexible blend component or a comonomer to improve the insufficient thermoplasticity of semirigid s‐BPDA/PDA homo polymer. The blends composed of s‐BPDA/PDA (80%) with a‐BPDA‐derived PIs (20%), as well as the s‐BPDA/PDA‐based copolymer containing 20% a‐BPDA, showed a certain extent of thermoplasticity above the T_gs without causing a decrease in T_g. In addition, these blends and copolymer provided comparatively low thermal expansion coefficient (ca. 18 ppm). The improved film properties for the blends are related to good blend miscibility. On the other hand, when s‐BPDA/ODA was used as a flexible matrix polymer instead of a‐BPDA‐derived PIs, the 80/20 blend film annealed at 400°C exhibited no prominent softening at the T_g. This result arises from annealing‐induced crystallization of the flexible s‐BPDA/ODA component. Thus, these results revealed that a‐BPDA‐derived PIs are promising candidates as matrix polymers for semirigid s‐BPDA/PDA for the present purpose. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2499–2511, 1999     

Superconducting properties in Rh17S15 under magnetic field and pressure

We have studied superconducting properties by measuring the electrical resistivity and magnetization for a single crystal of Rh₁₇S₁₅ with a superconducting transition temperature T_c=5.4 K. The upper critical field H_c2(0) and the lower critical field H_c1(0) were obtained as 20.5 and 0.0033 T, respectively. Correspondingly, the coherence length and the penetration depth were estimated to be 40 and 4900 Å, respectively, indicating that Rh₁₇S₁₅ is a typical type-II superconductor with strong correlations of conduction electrons with a 4d-electron character of Rh atoms. The present electron correlations are formed to be enhanced with increasing pressure.     

Indirect nuclear spin coupling between Cu++ pair in copper acetate monohydrate

The methods of molecular dynamics has been used to investigate the behaviour of transverse and longitudinal current-current autocorrelation functions in a model liquid simulating molten strontium chloride. Examples of the spectra of these functions are given and it is shown that the liquid propagates shear waves in a manner not unlike transverse phonons in crystals. The spectra of the mass and charge density, related to the spectra of the longitudinal currents, were computed. In both cases a non-central peak indicative of propagating acoustic and optic-type modes was observed for small wavenumbers, the optic-type mode persisting for larger wavenumbers than the acoustic-type modes. The possibility of observing these modes in inelastic neutron scattering experiments is discussed briefly.     

Galois module structure for dihedral extensions of degree 8: Realizable classes over the group ring

Let k be a number field with ring of integers O_k, and let Γ be the dihedral group of order 8. For each tame Galois extension N/k with group isomorphic to Γ, the ring of integers O_N of N determines a class in the locally free class group Cl(O_k[Γ]). We show that the set of classes in Cl(O_k[Γ]) realized in this way is the kernel of the augmentation homomorphism from Cl(O_k[Γ]) to the ideal class group Cl(O_k), provided that the ray class group of O_k for the modulus 4O_k has odd order. This refines a result of the second-named author (J. Algebra 223 (2000) 367-378) on Galois module structure over a maximal order in k[Γ].     

Magnetic nanomaterial–based electrochemical biosensors for the detection of diverse circulating cancer biomarkers

Electrochemical biosensors are highly compatible with modern advancements in magnetic nanomaterials. In particular, the versatile nature of magnetic nanomaterials as a universal platform for selective isolation of diverse forms of cancer biomarkers in body circulation, is highly synergistic with electrochemical biosensors for elevating biosensing performance to unprecedented levels. Such diverse circulating target biomolecules include cell surface proteins of circulating tumor cells and extracellular vesicles (EVs), as well as circulating tumor nucleic acids (i.e. ctDNA/ctRNA). This focussed review serves to discuss the latest work in the fields of magnetic nanomaterials and electrochemistry to tackle existing analysis challenges of diverse circulating biomarkers in cancer.