Purification of Curcumin from Ternary Extract-Similar Mixtures of Curcuminoids in a Single Crystallization Step

Crystallization-based separation of curcumin from ternary mixtures of curcuminoids having compositions comparable to commercial extracts was studied experimentally. Based on solubility and supersolubility data of both, pure curcumin and curcumin in presence of the two major impurities demethoxycurcumin (DMC) and bis(demethoxy)curcumin (BDMC), seeded cooling crystallization procedures were derived using acetone, acetonitrile and 50/50 (wt/wt) mixtures of acetone/2-propanol and acetone/acetonitrile as solvents. Starting from initial curcumin contents of 67–75% in the curcuminoid mixtures single step crystallization processes provided crystalline curcumin free of BDMC at residual DMC contents of 0.6–9.9%. Curcumin at highest purity of 99.4% was obtained from a 50/50 (wt/wt) acetone/2-propanol solution in a single crystallization step. It is demonstrated that the total product yield can be significantly enhanced via addition of water, 2-propanol and acetonitrile as anti-solvents at the end of a cooling crystallization process

Time-optimal synthesis of unitary transformations in coupled fast and slow qubit system

In this paper, we study time-optimal control problems related to system of two coupled qubits where the time scales involved in performing unitary transformations on each qubit are significantly different. In particular, we address the case where unitary transformations produced by evolutions of the coupling take much longer time as compared to the time required to produce unitary transformations on the first qubit but much shorter time as compared to the time to produce unitary transformations on the second qubit. We present a canonical decomposition of SU(4) in terms of the subgroup SU(2)xSU(2)xU(1), which is natural in understanding the time-optimal control problem of such a coupled qubit system with significantly different time scales. A typical setting involves dynamics of a coupled electron-nuclear spin system in pulsed electron paramagnetic resonance experiments at high fields. Using the proposed canonical decomposition, we give time-optimal control algorithms to synthesize various unitary transformations of interest in coherent spectroscopy and quantum information processing.Comment: 8 pages, 3 figure

ADN: An Information-Centric Networking Architecture for the Internet of Things

Forwarding data by name has been assumed to be a necessary aspect of an information-centric redesign of the current Internet architecture that makes content access, dissemination, and storage more efficient. The Named Data Networking (NDN) and Content-Centric Networking (CCNx) architectures are the leading examples of such an approach. However, forwarding data by name incurs storage and communication complexities that are orders of magnitude larger than solutions based on forwarding data using addresses. Furthermore, the specific algorithms used in NDN and CCNx have been shown to have a number of limitations. The Addressable Data Networking (ADN) architecture is introduced as an alternative to NDN and CCNx. ADN is particularly attractive for large-scale deployments of the Internet of Things (IoT), because it requires far less storage and processing in relaying nodes than NDN. ADN allows things and data to be denoted by names, just like NDN and CCNx do. However, instead of replacing the waist of the Internet with named-data forwarding, ADN uses an address-based forwarding plane and introduces an information plane that seamlessly maps names to addresses without the involvement of end-user applications. Simulation results illustrate the order of magnitude savings in complexity that can be attained with ADN compared to NDN.Comment: 10 page

Sudakov Resummations in Mueller-Navelet Dijet Production

In high energy hadron-hadron collisions, dijet production with large rapidity separation proposed by Mueller and Navelet, is one of the most interesting processes which can help us to directly access the well-known Balitsky-Fadin-Kuraev-Lipatov evolution dynamics. The objective of this work is to study the Sudakov resummation of Mueller-Navelet jets. Through the one-loop calculation, Sudakov type logarithms are obtained for this process when the produced dijets are almost back-to-back. These results could play an important role in the phenomenological study of dijet correlations with large rapidity separation at the LHC.Comment: 20 pages, 5 figures; v2, refs adde

Microscopic Theory of the Single Impurity Surface Kondo Resonance

We develop a microscopic theory of the single impurity Kondo effect on a metallic surface. We calculate the hybridization energies for the Anderson Hamiltonian of a magnetic impurity interacting with surface and bulk states and show that, contrary to the Kondo effect of an impurity in the bulk, the hybridization matrix elements are strongly dependent on the momentum around the Fermi surface. Furthermore, by calculating the tunneling conductance of a scanning tunneling microscope (STM), we show that when the magnetic impurity is located at a surface the Kondo effect can occur with equal strength between bulk and surface states. We compare our results with recent experiments of Co impurities in Cu(111) and Cu(100) surfaces and find good quantitative agreement.Comment: New version of the original manuscript with extended discussions on the problem of wavefunction orthogonality, the limitations of the theory, more figures related to the STM experiments, and one correction to an earlier result. Accepted for publication in Phys.Rev.

Infrared phonons and specific heat in Ba3Cr2O8

We report on the phonon spectrum of Ba3Cr2O8 determined by infrared spectroscopy, and on specific heat measurements across the Jahn-Teller transition in magnetic fields up to 9 T. Phonon modes split below the Jahn-Teller transition, which occurs at T_{JT} = 70 K as detected by specific heat measurements. The field-dependent specific heat data is analyzed in terms of the contributions from lattice, magnetic and orbital degrees of freedom. In contrast to the isostructural compound Sr3Cr2O8 our analysis does not indicate the existence of orbital fluctuations below the Jahn-Teller transition in Ba3Cr2O8.Comment: 5 pages, 4 figure