Onset of a pseudogap regime in ultracold Fermi gases

We show, using an ab initio approach based on Quantum Monte Carlo technique, that the pseudogap regime emerges in ultracold Fermi gases close to the unitary point. We locate the onset of this regime at a value of the interaction strength corresponding to (k(F)a)(-1)≈-0.05 (a-scattering length). We determine the evolution of the gap as a function of temperature and interaction strength in the Fermi gas around the unitary limit and show that our results exhibit a remarkable agreement with the recent wave-vector resolved radio frequency spectroscopy data. Our results indicate that a finite temperature structure of the Fermi gas around unitarity is more complicated and involves the presence of the phase with preformed Cooper pairs, which, however, do not contribute to the long range order.     

Facile synthesis of sterically hindered and electron-deficient secondary amides from isocyanates

The big easy: The direct coupling of Grignard reagents to isocyanates provides a facile and robust solution for the synthesis of sterically hindered and electron-deficient secondary amides. The products are obtained in high yields without the need for excess reagents or chromatographic purification.     

Multipartite entanglement inequalities via spin vector geometry

We introduce inequalities for multipartite entanglement, derived from the geometry of spin vectors. The criteria are constructed iteratively from cross and dot products between the spins of individual subsystems, each of which may have arbitrary dimension. For qubit ensembles the maximum violation for our inequalities is larger than that for the Mermin-Klyshko Bell inequalities, and the maximally violating states are different from Greenberger-Horne-Zeilinger states. Our inequalities are violated by certain bound entangled states for which no Bell-type violation has yet been found.     

Some free iminoxyl radicals in the hydrogenated pyridine series

Summary Five new free radicals of the hydrogenated pyridine series were synthesized and their reaction with phenylhydrazine was studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 391–393, February, 1965     

Dynamics of molecules in strong oscillating electric fields using time-dependent Hartree-Fock theory

Restricted and unrestricted forms of time-dependent Hartree-Fock theory have been implemented and used to study the electronic dynamics of ethene, benzene, and the formaldehyde cation subjected to both weak and strong oscillating electric fields. Absorption spectra and frequency-dependent polarizabilities are calculated via the instantaneous dipole moment and its derivative. In the weak field limit the computed excitation energies agree very well with those obtained using linearized time-dependent Hartree-Fock theory, which is valid only in the low-field perturbation limit. For strong fields the spectra show higher-order excitations, and a shift in the position of the excitations, which is due to the nonadiabatic response of the molecules to the field. For open-shell systems in the presence of strong oscillating electric fields, unrestricted time-dependent Hartree-Fock theory predicts the value of S(2) to vary strongly with time.     

Adsorption of endotoxins on Ca2+ iminodiacetic acid by metal ion affinity chromatography

Endotoxins (also known as lipopolysaccharides (LPS)) are undesirable by products of recombinant proteins, purified from Escherichia coli. LPS can be considered stable under a wide range of temperature and pH, making their removal one of the most difficult tasks in downstream processes during protein purification. The inherent toxicity of LPS makes their removal an important step for the application of these proteins in several biological assays and for a safe parenteral administration. Immobilized metal affinity chromatography (IMAC) enables the affinity interactions between the metal ions (immobilized on the support through the chelating compound) and the target molecules, thus enabling high efficiency separation of the target molecules from other components present in a mixture. Affinity chromatography is applied with Ca2+ iminodiacetic acid (IDA) to remove most of the LPS contaminants from the end product (more than 90%). In this study, the adsorption of LPS on an IDA-Ca2+was investigated. The adsorption Freundlich isotherm of LPS-IDA-Ca2+provides a theoretical basis for LPS removal. It was found that LPS is bound mainly by interactions between the phosphate group in LPS and Ca2+ligands on the beads. The factors such as pH (4.0 or 5.5) and ionic strength (1.0 mol/L) are essential to obtain effective removal of LPS for contaminant levels between endotoxin’ concentration values less than 100 EU/mL and 100000 EU/mL. This new protocol represents a substantial advantage in time, effort, and production costs.     

Spin-induced angular momentum switching

When light is transmitted through optically inhomogeneous and anisotropic media the spatial distribution of light can be modified according to its input polarization state. A complete analysis of this process, based on the paraxial approximation, is presented, and we show how it can be exploited to produce a spin-controlled change in the orbital angular momentum of light beams propagating in patterned space-variant optical axis phase plates. We also unveil a new effect: the development of a strong modulation in the angular momentum change upon variation of the optical path through the phase plates.