Separation of polyphenols using porous polyamide resin and assessment of mechanism of retention

A porous polyamide resin is shown to possess hydrogen bond acceptor properties suitable for the separation of polyphenolic solutes such as phenolic acids, flavonols and flavonoids. The separation is achieved in the presence of solvent mixtures of acetic acid and ethanol. The extent of hydrogen bond adsorption is reviewed based on data obtained from the elution behaviour of a variety of simple polyphenolic solutes. Polyamide adsorption chromatography was applied for the purification of resveratrol and polydatin from Polygonum cuspidatum Sieb. & Zucc.     

Nonadiabatic alignment of asymmetric top molecules: rotational revivals

The rotational revival structure of asymmetric top molecules, following irradiation by an intense picosecond laser pulse, is explored theoretically and experimentally. Numerically we solve nonperturbatively for the rotational dynamics of a general asymmetric top subject to a linearly polarized intense pulse, and analyze the dependence of the dynamical alignment on the field and system parameters. Experimentally we use time-resolved photofragment imaging to measure the alignment of two molecules with different asymmetry, iodobenzene, and iodopentafluorobenzene. Our numerical results explain the experimental observations and generalize them to other molecules. The rotational revival structure of asymmetric tops differs qualitatively from the intensively studied linear top case. Potentially it provides valuable structural information about molecules.     

Azin­yl sulfides. LXXXI. 14‐Phen­yl‐7‐thia­pyrano[2,3‐c;6,5‐c′]diquinoline‐14‐carbonitrile

The mol­ecules of the title compound, C₂₆H₁₅N₃S, have a penta­cyclic ring system which is almost planar, with the central ring in a flattened boat conformation. The folding angle between the two quinoline rings is 6.75 (7)°. The 14‐phen­yl substituent is in a quasi‐axial conformation, while the 14‐cyano substituent is in a quasi‐equatorial conformation with respect to the thio­pyran ring. The S⋯C—C_phen­yl and S⋯C—C_CN angles are 116.8 (2) and 129.3 (2)°, respectively. The plane of the phen­yl group is nearly coplanar with the plane bis­ecting the dihedral angle of the penta­cyclic ring system.     

Hydrophilic Carotenoids: Surface Properties and Aggregation Behavior of the Potassium Salt of the Highly Unsaturated Diacid Norbixin

The oft‐claimed ‘good’ water solubility of the food color norbixin ( 3 ) could not be confirmed. In contrast, the potassium salt 5 of norbixin formed suitable dispersions. The surface and aggregation properties of salt 5 were investigated and compared with other naturally occurring and synthetic hydrophilic carotenoids (Table).     

Domains of holomorphy for Fourier transforms of solutions to discrete convolution equations

We study solutions to convolution equations for functions with discrete support in R~n, a special case being functions with support in the integer points. The Fourier transform of a solution can be extended to a holomorphic function in some domains in C~n, and we determine possible domains in terms of the properties of the convolution operator.     

Hydrogen-bond driven assembly of a molecular capsule facilitated by supramolecular chelation

Resorcinarene-based cavitands functionalized with acetamido groups capable of self-complementary hydrogen-bond interactions, were synthesized in order to construct supramolecular capsules. The 1,3-bifunctionalized cavitand produced a polymeric assembly, whereas the tetra-functionalized analogue yielded a discrete capsule held together via N-H···O hydrogen bonds. The ethynyl species attached to the rim of these host molecules deepen each cavitand and expands the volume of the resulting capsule.     

Experience with a Stochastic Replacement Model

This paper reports on a study initiated to check the validity of an existing six-monthly block replacement policy for a set of filling valves in a canning line. After dealing with inadequacies in the data and changing to a production-based time measure, the paper shows how a renewal function measure of the expected number of valve replacements was obtained and led to the conclusion that the current block replacement policy could not be justified.The possibility of an age-based replacement policy being of value remained. In order to model such a policy, it was necessary to reverse the usual analysis of renewal-type processes in that an estimate was required of the distribution function of time between renewals, given the renewal function.A finite optimal replacement age was found which depended upon the objective being to minimize a measure of downtime due to replacements, or operating costs attributable to replacements. Calculations were further complicated by part of the plant having a finite remaining life before being upgraded.