Quantum Logics that are Symmetric-difference-closed

International Journal of Theoretical Physics - In this note we contribute to the recently developing study of “almost Boolean” quantum logics (i.e. to the study of orthomodular...     

Nanomaterial-based biosensors for detection of prostate specific antigen

Screening serum for the presence of prostate specific antigen (PSA) belongs to the most common approach for the detection of prostate cancer. This review (with 156 refs.) addresses recent developments in PSA detection based on the use of various kinds of nanomaterials. It starts with an introduction into the field, the significance of testing for PSA, and on current limitations. A first main section treats electrochemical biosensors for PSA, with subsections on methods based on the use of gold electrodes, graphene or graphene-oxide, carbon nanotubes, hybrid nanoparticles, and other types of nanoparticles. It also covers electrochemical methods based on the enzyme-like activity of PSA, on DNA-, aptamer- and biofuel cell-based methods, and on the detection of PSA via its glycan part. The next main section covers optical biosensors, with subsections on methods making use of surface plasmon resonance (SPR), localized SPR and plasmonic ELISA-like schemes. This is followed by subsections on methods based on the use of fiber optics, fluorescence, chemiluminescence, Raman scattering and SERS, electrochemiluminescence and cantilever-based methods. The most sensitive biosensors are the electrochemical ones, with lowest limits of detection (down to attomolar concentrations), followed by mass cantilever sensing and electrochemilumenescent strategies. Optical biosensors show lower performance, but are still more sensitive compared to standard ELISA. The most commonly applied nanomaterials are metal and carbon-based ones and their hybrid composites used for different amplification strategies. The most attractive sensing schemes are summarized in a Table. The review ends with a section on conclusions and perspectives.

Open image in new window

Graphical abstract Schematic representation of nanostructure-based biosensors for detection of prostate specific antigen using various detection schemes and biorecognition elements such as antibodies (Abs), aptamers (APT), lectins (LEC), and molecularly imprinted polymers (MIP).

     

The many faces of radiation‐induced changes

During diffraction experiments even cryo‐cooled protein crystals can be significantly damaged due to chemical and physical changes induced by absorbed X‐ray photons. The character and scale of the observed effects depend strongly on the temperature and the composition of crystals. The absorption of radiation energy results in incremental regular changes to the crystal structure, making its impact on the process of solving the structure strongly correlated with other experimental variables. An understanding of all the dependencies is still limited and does not allow for a precise prediction of the outcome of a particular diffraction experiment. Results are presented of diffraction experiments performed under different experimental conditions. The influence of temperature and crystal composition on different characteristics of radiation damage is analyzed. The observed effects are discussed in terms of their impact on data processing and phasing procedures.     

Non-parametric multivariate analysis of variance in the proteomic response of potato to drought stress

Spot detection is a mandatory step in all available software packages dedicated to the analysis of 2D gel images. As the majority of spots do not represent individual proteins, spot detection can obscure the results of data analysis significantly. This problem can be overcome by a pixel-level analysis of 2D images.     

Comparison of different imidazolium supported ionic liquid polymeric phases with strong anion-exchange character for the extraction of acidic pharmaceuticals from complex environmental samples

Two imidazolium supported ionic liquid phases (SILPs) containing different anions, trifluoromethanesulphonate [CF(3) SO(3) (-) ], and tetrafluoroborate [BF(4) (-) ], were synthesized and evaluated as solid-phase extraction sorbents for extracting acidic pharmaceuticals from aqueous samples under strong anion-exchange conditions, which include an effective cleanup of the sample. The best SILP material [MI(+) ][CF(3) SO(3) (-) ] was selected and successfully applied to the determination of acidic pharmaceuticals in different types of water samples (river water and effluent wastewater). The results were then compared to the previously synthesized SILP material based on [MI(+) ][CF(3) COO(-) ] and the commercially available Oasis MAX sorbent.     

Self-similar asymptotics of solutions to heat equation with inverse square potential

We show that the large-time behavior of solutions to the Cauchy problem for the linear heat equation with the inverse square potential is described by explicit self-similar solutions.     

Influence of applied potential on bradykinin adsorption onto Ag,Au, and Cu electrodes

Surface‐enhanced Raman scattering, electrochemistry, and generalized two‐dimensional correlation analysis (G2DCA) methods were used to characterize bradykinin (BK), a hormone which is known to be involved in small‐cell and non‐small‐cell lung carcinoma and prostate cancer. BK was deposited onto Ag, Au, and Cu electrode surfaces under different applied electrode potentials (−1.000 V to 0.200 V) in aqueous solutions. Based on the analysis of the enhancement, the broadening, and the shifts in the wavenumbers of individual bands, specific conclusions were drawn regarding the peptide geometry and changes in this geometry that occurred when the electrode type and applied electrode potential were varied. Briefly, BK deposited onto the Ag, Au, and Cu electrode surfaces showed bands that were due to the vibrations of moieties in contact with or in close proximity to the electrode surfaces and were thus located on the same side of the polypeptide backbone. These moieties included the Phe, Arg, and Pro residues. The findings for adsorbed BK were fully supported by G2DCA, which also allowed us to determine the order in which changes occurred when the electrode potential was changed. In addition, it was found that at negative electrode potentials, the Phe rings and methylene groups interact with Ag electrode surface. No such interaction was observed for Au and Cu electrodes. Copyright © 2013 John Wiley & Sons, Ltd.     

Atomistic molecular dynamics simulations on the interaction of TEMPO-oxidized cellulose nanofibrils in water

Atomistic molecular dynamics simulations were carried out to obtain information on the rheological, aggregation and disintegration properties of carboxylated (TEMPO-oxidized) cellulose nanofibrils with different functionalization levels. The magnitude of the inter-fibril interaction was quantified for parallel nanofibrils using the umbrella sampling method. The obtained potential of mean force was found highly sensitive to the charge configuration for intermediate functionalization levels. This feature was further studied with an electrostatic model for similar charge configurations and system periodicity as in the case of the molecular dynamics simulations. The electrostatic contribution of the charged surfaces varied from repulsive to attractive depending on the distribution of the carboxylate groups and nearby counter-ions, as well as the distance between the fibrils. The simulated deviations from average behavior for single fibrils in both models suggest heterogeneity in their aggregation and disintegration behavior. This was seen in disintegration experiments, where the differences in disintegration energy and in the structural variation qualitatively agreed with the model predictions. As to aggregation behavior, the studied case with parallel fibrils reflects the upper boundary of the repulsive interaction.