Medium-sized double magic metal clusters, Al@Ag(54) (-) and Al@Cu(54) (-), are predicted based on unbiased global search and density functional calculation. Both bimetallic core-shell clusters have icosahedral symmetry, and they are much lower in energies than all other low-lying isomers. In contrast, the icosahedral cluster Al@Au(54) (-) is a high-energy isomer. Both Al@Ag(54) (-) and Al@Cu(54...

Dietary lycopene consists mostly of the (all-E) isomer. Upon absorption, (all-E) lycopene undergoes isomerisation into various (Z)-isomers. Because these isomers offer potentially better health benefits than the (all-E) isomer, the aim of the present study was to investigate if the profile of lycopene isomers in intestinal lipoproteins is affected by the profile of lycopene isomers in the meal ...

many properties of chemicals depend on their streochemistry. among these, the effects of streoisomerism on percutaneous absorption of drugs, which is subject of the present investigation, is not well studied yet. in this study, tretinoin (tt) and isotretinoin (itt) (geometric isomers) were chosen and their permeations (alone or in the presence of each other) through enhancer-treated excised rat...

Eleven mice were trained to respond under an FR 20 schedule of reinforcement and, after learning the schedule, were administered doses of saline and the following phenylisopropylamines: (+/-)-MDMA, S(+)-MDMA, R(-)-MDMA and (+)-amphetamine. Each of the phenylisopropylamines decreased rates of operant responding in a dose-dependent manner. S(+)-MDMA (ED50 = 3.1 mg/kg) was nearly equipotent with r...

Ab initio calculations of the optical rotatory power of the natural cytokine modulator cytoxazone 1 and its trans-diastereomer 2, as well as the structural isomers cis-3 and trans-4 isocytoxazones, have been performed at four different wavelengths (589, 546, 435, and 405 nm) by Density Functional Theory. The calculation of ORD curves provides a reliable method for the assignment of absolute con...

Chloramphenicol, an inhibitor of mitochondrial protein synthesis, shortened the period length of the circadian rhythm in the Timex strain of Neurospora crassa by 2 hours. Both the l(+) threo and d(-) threo optical isomers had the same effect on the period of the rhythm, whereas only the d(-) threo isomer significantly inhibited mitochondrial protein synthesis. Tetracycline, another inhibitor of...

Optical absorption spectra have been calculated for a series of boron nitride fullerenelike cage structures BnNn of sizes n=12-36. The method used is a real-time, real-space implementation of the time-dependent density-functional theory, involving the full time propagation of the time-dependent Kohn-Sham equations. The spectra are found to be a possible tool for distinguishing between different...

The optical spectra of sandwich clusters formed by transition metal atoms (titanium, vanadium, and chromium) intercalated between parallel benzene molecules have been studied by time-dependent density functional theory (TDDFT) and many-body perturbation theory. Sandwiches with different number of layers, including infinite chains, are considered. The lowest excitation energy peaks in the spectr...