Epoxy-functionalized large-pore SBA-15 and KIT-6 as affinity chromatography supports

Mesoporous silica supports are proposed as an alternative to polymeric stationary phases for fast affinity chromatography due to their better mechanical strength compared to polymers. Ideal supports should combine high surface area and large pore size to allow a high loading capacity of large molecules, such as proteins, and favor their accessibility. Increasing the pore size of large-surface area micelle-templated silicas (SBA-15, KIT-6) has been achieved by swelling the micelles by the addition of organic molecules and increasing synthesis time and temperature. The pore size of hexagonal silica mesostructured SBA-15 has been increased up to 35 nm. These materials could find therefore application as affinity chromatography for immunoextraction.     

Parity-broken chiral spin dynamics in Ba₃NbFe₃Si₂O₁₄

The spin-wave excitations emerging from the chiral helically modulated 120° magnetic order in a langasite Ba?NbFe?Si?O?? enantiopure crystal were investigated by unpolarized and polarized inelastic neutron scattering. A dynamical fingerprint of the chiral ground state is obtained, singularized by (i) spectral weight asymmetries answerable to the structural chirality and (ii) a full chirality of the spin correlations observed over the whole energy spectrum. The intrinsic chiral nature of the spin waves' elementary excitations is shown in the absence of macroscopic time-reversal symmetry breaking.     

Methods and evaluation of frequency aging in distributed-feedback laser diodes for rubidium atomic clocks

Distributed-feedback laser diodes emitting at 780?nm have been evaluated, with respect to the aging of the injection current required for reaching the rubidium D2 resonance line. Results obtained for lasers operating in air and in vacuum for 9 months are reported. When operated at constant temperature, the laser current required for emission at the wavelength of the desired atomic resonance is found to decrease by 50 to 80?μA per month. The impact of this result on the lifetime and long-term performances of laser-pumped rubidium atomic clocks is discussed.     

Synthesis of linear and hyperbranched sugar‐grafted polysiloxanes using N‐hydroxysuccinimide‐activated esters

A straightforward method for the preparation of polysiloxanes grafted with carbohydrate side groups is described. Two kinds of backbones have been functionalized, namely one‐dimensional, linear polysiloxanes, and hyperbranched poly(siloxysilane)s based on cyclotetrasiloxanes. The method enables us to keep a good integrity of the polysiloxane backbone. The introduction of intermediate activated esters as side groups on the polysiloxane backbone ensures a complete homogeneity of the reaction medium during sugar grafting in dimethyl sulfoxide, and consequently an easy grafting with the unprotected amino sugar. Solubility of the resulting polysiloxanes has been tested in various solvents. The sugar‐grafted polysiloxanes are good candidates for applications such as silicone formulations, hydrophilic silicone elastomers, interactions with metallic nanoparticles, and suspension stabilization, or as starting point for the design of more complex polysiloxanes for molecular recognition. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3607–3618     

Design and synthesis of novel spirocyclopropyl cyclohexane-1,3-diones and -1,3,5-triones for their incorporation into potent HPPD inhibitors

We report the design and the efficient synthesis of novel spirocyclopropyl cyclohexane-1,3-dione and -1,3,5-trione units to be incorporated into potent HPPD inhibitors. New routes involving original combinations of synthetic equivalents of α-cyclopropyl ketone-α-anion and α-cyclopropyl ester-β-cation are described.     

Magnetic and magnetooptical properties of Au/Cu-wedge/15-Å-NiFe sandwiches

The results of an investigation of the magnetic and magnetooptical properties of Au/Cu-wedge/15-Å-NiFe sandwiches are reported. Oscillations of the equatorial Kerr effect as a function of the copper wedge thickness are observed. The period of these oscillations is found to be of the order of 5–6 Å. The experimentally observed oscillations of the equatorial Kerr effect are attributed to a quantum size effect. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 1, 33–36 (10 January 1998)     

Accurate estimation of solvation free energy using polynomial fitting techniques

This report details an approach to improve the accuracy of free energy difference estimates using thermodynamic integration data (slope of the free energy with respect to the switching variable λ) and its application to calculating solvation free energy. The central idea is to utilize polynomial fitting schemes to approximate the thermodynamic integration data to improve the accuracy of the free energy difference estimates. Previously, we introduced the use of polynomial regression technique to fit thermodynamic integration data (Shyu and Ytreberg, J Comput Chem, 2009, 30, 2297). In this report we introduce polynomial and spline interpolation techniques. Two systems with analytically solvable relative free energies are used to test the accuracy of the interpolation approach. We also use both interpolation and regression methods to determine a small molecule solvation free energy. Our simulations show that, using such polynomial techniques and nonequidistant λ values, the solvation free energy can be estimated with high accuracy without using soft‐core scaling and separate simulations for Lennard‐Jones and partial charges. The results from our study suggest that these polynomial techniques, especially with use of nonequidistant λ values, improve the accuracy for ΔF estimates without demanding additional simulations. We also provide general guidelines for use of polynomial fitting to estimate free energy. To allow researchers to immediately utilize these methods, free software and documentation is provided via http://www.phys.uidaho.edu/ytreberg/software . © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010