Heterogeneous Electrofreezing Triggered by CO2 on Pyroelectric Crystals: Qualitatively Different Icing on Hydrophilic and Hydrophobic Surfaces

By performing icing experiments on hydrophilic and hydrophobic surfaces of pyroelectric amino acids and on the x‐cut faces of LiTaO₃, we discovered that the effect of electrofreezing of super cooled water is triggered by ions of carbonic acid. During the cooling of the hydrophilic pyroelectric crystals, a continuous water layer is created between the charged hemihedral faces, as confirmed by impedance measurements. As a result, a current of carbonic acid ions, produced by dissolved environmental CO₂, flows through the wetted layer towards the hemihedral faces and elevates the icing temperature. This proposed mechanism is based on the following: (i) on hydrophilic surfaces, water with dissolved CO₂ (pH 4) freezes at higher temperatures than pure water of pH 7. (ii) In the absence of the ionic current, achieved by linking the two hemihedral faces of hydrophilic crystals by a conductive paint, water of the two pH levels freeze at the same temperature. (iii) On hydrophobic crystals with similar pyroelectric coefficients, where there is no continuous wetted layer, no electrofreezing effect is observed.     

Super-Enhancement Focusing of Teflon Spheres

A Teflon (polytetrafluoroethylene) sphere can be used as a focusing lens in the applications of imaging and sensing due to its low-loss property in the terahertz band. Herein, field intensities and focusing parameters are analytically calculated for Teflon spheres at different low-loss levels and then a super-enhancement focusing effect in the spheres with particular size parameters was discovered, which can stimulate about 4000 times stronger field intensity than that for incident radiation as well as the great potential of overcoming diffraction limit despite high sensitivity to the magnitude of Teflon loss. A subsequent analysis of scattering amplitudes proves that the strong scattering of a single-order mode in the internal electric or magnetic field is the main factor causing this phenomenon.     

Two possible ways to combine boron and gadolinium for Gd-guided BNCT. A concept

Abstract

Two ways of synthesis of theragnostic compounds for Gd-guided boron neutron capture therapy of cancer are proposed. The first way is based on modification of DO3A ligand, which a capable to form stable complexes with gadolinium, with attachment of boron-containing moieties and additional functional groups which can be used for conjugation with various biomacromolecules. The second way is based on the introduction of additional chelating groups into a boron-containing moiety—carborane-based ligand. It is expected that this will significantly improve the stability of the gadolinium bis(dicarbollide) complexes.     

Reaction of sodium N-benzylideneglycinate with dialkyl chlorophosphites in the presence of water

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Immobilisation of Clostridium spp. for production of solvents and organic acids

This review summarises the high potential of immobilised cells systems for the fermentative production of compounds, mainly produced by representatives of the Clostridium genus. Microorganisms of Clostridium species are recognised as good producers of a wide range of chemicals in almost every sector of industry. The combination of this microorganism with its immobilisation opens up new possibilities and renders the fermentation process more sophisticated than in a free-cell system. This review provides a comprehensive summary of techniques used in immobilisation of Clostridium species with regard to specific products and types of fermentation. In addition, comparisons of particular types of immobilisation techniques used in fermentation processes are summarised by specific products.     

Phospho‐l‐tyrosine‐agarose chromatography: Adsorption of human IgG and its proteolytic fragments

The behavior of human immunoglobulin G (IgG) and antigen‐binding fragment (Fab fragment) adsorption onto phospho‐l ‐tyrosine immobilized on agarose (P‐Tyr‐agarose) was evaluated by pseudoaffinity chromatography. The effects of buffer systems MES, MOPS, Bis–Tris, Tris–HCl and sodium phosphate (NaP) and pH on IgG adsorption were studied and high purity values were obtained (96%, based on ELISA analysis of albumin, transferrin and immunoglobulins A, G and M) when IgG was purified from human plasma diluted in 10 mmol L^?1 NaP buffer at pH 6.0. The capture of IgG by the P‐Tyr‐agarose was also promising, since 91% of the IgG was adsorbed when plasma was diluted in 25 mmol L^?1 MES buffer at pH 5.5, recommending its use for IgG depletion from human plasma under this condition. The experimental data on IgG adsorption kinetics were in agreement with the pseudo‐second‐order model. The adsorption isotherm data were well described by the Langmuir–Freundlich model with the value of parameter n being <1 (0.72), indicating negative cooperativity. Selectivity was achieved on P‐Tyr‐agarose from digested human IgG in HEPES 25 mmol L^?1 buffer at pH 7.0 where Fab fragments were obtained in eluted fractions without Fc fragments (but with uncleaved IgG) with 86.2% recovery.     

Polynomials with integer coefficients and their zeros

We study several related problems on polynomials with integer coefficients. This includes the integer Chebyshev problem, and the Schur problems on means of algebraic numbers. We also discuss interesting applications to the approximation by polynomials with integer coefficients, and to the growth of coefficients for polynomials with roots located in prescribed sets. The distribution of zeros for polynomials with integer coefficients plays an important role in all of these problems.     

XO: An extended ONIOM method for accurate and efficient modeling of large systems

Calculation of large complex systems remains to be a great challenge, where there is always a trade‐off between accuracy and efficiency. Recently, we proposed the extended our own n‐layered integrated molecular orbital (ONIOM) method (XO) (Guo, Wu, Xu, Chem. Phys. Lett. 2010 , 498, 203) which surmounts some inherited limitations of the popular ONIOM method by introducing the inclusion‐exclusion principle used in the fragmentation methods. The present work sets up general guidelines for the construction of a good XO scheme. In particular, force‐error test is proposed to quantitatively validate the usefulness of an XO scheme, taking accuracy, efficiency and scalability all into account. Representative studies on zeolites, polypeptides and cyclodextrins have been carried out to demonstrate how to strive for high accuracy without sacrificing efficiency. As a natural extension, XO is applied to calculate the total energy, fully optimized geometry and vibrational spectra of the whole system, where ONIOM becomes inapplicable. © 2012 Wiley Periodicals, Inc.     

3D dif fractive lenses to overcome the 3D Abbe subwavelength dif fraction limit

The innovative radiating structures as a conical millimeter wave FZP lens are proposed for subwavelength focusing.The results of FDTD simulation and experimental verification are discussed.It has been shown that in contrast to the flat diffractive optics the curvilinear 3D diffractive conical optics is capable of overcoming 3D Abbe barrier with a focal distance F greater than 2λ.The focal intensity distribution for such type of lenses is not circularly symmetric and thus the focal spot in the high numerical aperture case is no longer an Airy pattern.These results may find useful applications in optical microscopes,including"reverse-microscope",nondestructive testing,microoptics,and nanooptics.