Aurones: interesting natural and synthetic compounds with emerging biological potential

Aurones [2-benzylidenebenzofuran-3(2H)-ones] are either natural or synthetic compounds, belonging to the flavonoid family. They are isomeric to flavones and provide a bright yellow color to the plants in which they occur. Today, a literature survey indicates that the related flavonoids have been studied not only for their physiological properties and effects on Nature, but also for their therapeutic potential. Aurones are recently attracting the interest of an increasing number of research groups, and, since the last review, some interesting advances have been made in understanding the aurones. In this review, we report the recent advances made on the synthetic routes towards aurones. We also highlight their activity in different biological areas, as well as applied genetic plant modifications to produce these colored compounds. Their synthesis, structure-activity relationships and the importance of the substitution pattern will also be mentioned. Finally, some aspects regarding the possible development of aurones will be discussed briefly.     

Ni2Sn2Zn from single‐crystal X‐ray diffraction

Dinickel ditin zinc, Ni₂Sn₂Zn, crystallizes in the cubic space group , with a lattice parameter of a = 8.845 (1) Å and with all atoms occupying special positions. The crystal structure exhibits pronounced similarities with that of the quaternary compound Ni_5.20Sn_8.7Zn_4.16Cu_1.04. It shares structural features with other compounds in the Ni–Sn–Zn system, such as Ni₅Sn₄Zn and Ni₃Sn₂.     

Nimustine hydrochloride: the first crystal structure determination of a 2‐chloroethyl‐N‐nitrosourea hydrochloride derivative by X‐ray powder diffraction and solid‐state NMR

Nimustine hydrochloride [systematic name: 4‐amino‐5‐({[N‐(2‐chloroethyl)‐N‐nitrosocarbamoyl]amino}methyl)‐2‐methylpyrimidin‐1‐ium chloride], C₉H₁₄ClN₆O₂⁺·Cl⁻, is a prodrug of CENU (chloroethylnitrosourea) and is used as a cytostatic agent in cancer therapy. Its crystal structure was determined from laboratory X‐ray powder diffraction data. The protonation at an N atom of the pyrimidine ring was established by solid‐state NMR spectroscopy.     

Enantioselective synthesis of Garner's aldehyde by asymmetric hydroformylation

Both enantiomers of Garner's aldehyde (3) are prepared from the same alkene 4 by catalytic asymmetric hydroformylation.     

Live Monitoring of Cargo Release From Peptide‐Based Hybrid Nanocapsules Induced by Enzyme Cleavage

The miniemulsion process is used as a new route for the preparation of enzyme‐responsive nanocapsules with payload‐release properties. Peptide‐based hybrid nanocapsules are prepared via interfacial polyaddition containing a water‐soluble dye that is efficiently encapsulated inside. The influence of the synthetic parameters as the functionality of the peptide and the nature of the dispersed phase on the structure of the nanocapsules were investigated. After redispersion in water, the enzymatic cleavage of the peptide sequence and the release of the fluorescent dye are both monitored in real time. This is evidenced because of the quenching FRET system framing the recognition site in the peptide sequence, and the fluorescence recovery of the self‐quenched encapsulated dye respectively.     

Solving the post enrolment course timetabling problem by ant colony optimization

In this work we present a new approach to tackle the problem of Post Enrolment Course Timetabling as specified for the International Timetabling Competition 2007 (ITC2007), competition track 2. The heuristic procedure is based on Ant Colony Optimization (ACO) where artificial ants successively construct solutions based on pheromones (stigmergy) and local information. The key feature of our algorithm is the use of two distinct but simplified pheromone matrices in order to improve convergence but still provide enough flexibility for effectively guiding the solution construction process. We show that by parallelizing the algorithm we can improve the solution quality significantly. We applied our algorithm to the instances used for the ITC2007. The results document that our approach is among the leading algorithms for this problem; in all cases the optimal solution could be found. Furthermore we discuss the characteristics of the instances where the algorithm performs especially well.     

Multiple right-hand side techniques for the numerical simulation of quasistatic electric and magnetic fields

The simulation of slowly varying transient electric high-voltage fields and magnetic fields requires the repeated and successive solution of high-dimensional linear algebraic systems of equations with identical or near-identical system matrices and different right-hand side vectors. For these solution processes which are required within implicit time integration schemes and nonlinear (quasi-)Newton–Raphson methods an iterative multiple right-hand side (mrhs) scheme is used which recycles vector subspaces resulting from previous preconditioned conjugate gradient iteration runs. The combination of this scheme with a subspace projection extrapolation start value generation scheme is discussed. Numerical results for three-dimensional electric and magnetic field simulations are presented and the efficiency of the new schemes re-using eigenvector information from previous iteration processes with different tolerance criteria are compared to those of standard conjugate gradient iterations.