A Problem in Vehicle Fuel Consumption

The application is described of two alternative methods of solution, employing Dynamic Programming and Lagrange's Multipliers, respectively, to a problem of calculating the minimum fuel consumption of a bus fleet. In essence the problem is how to divide up the time scheduled for a complete journey amongst the intermediate sections in order to minimize the total fuel consumption.     

Alkenylpyridine and alkenylamine complexes of palladium

Addition of alkenylamines and alkenylpyridines to trans-[PdCl₂(coe)]₂ (1) (coe = C₈H₁₄) afforded complexes of the type trans-PdCl₂L₂ (where L is a nitrogen-containing ligand). Coordination of the alkenylamine or alkenylpyridine groups occurred primarily through the nitrogen atom in all cases. Addition of aminopropylvinylether (apve = H₂NCH₂CH₂CH₂OCH=CH₂) to (1) gave trans-PdCl₂(thmo)₂ (9) (thmo = tetrahydro-2-methyl-1,3-oxazine) via an intramolecular hydroamination.     

Rapid identification of antibacterial agents effective against Staphylococcus aureus using small-molecule macroarrays

There is an urgent, global need for the development of new antibacterial agents. We have applied the small-molecule macroarray approach to the synthesis and screening of antibacterial compounds active against the Gram-positive pathogen Staphylococcus aureus. Several macroarrays of 1,3-diphenyl-2-propen-1-ones (chalcones), cyanopyridines, and pyrimidines were synthesized on a planar cellulose support system on the order of days. This support system was found to be highly compatible with antibacterial assay formats, including disk-diffusion and agar-overlay visualization methods. Further, sufficient compound was isolated from each spot of the macroarray for both compound characterization and minimum inhibitory concentration (MIC) estimation. Analysis of the small-molecule macroarrays in these assays uncovered a set of antibacterial agents with in vitro MIC values against methicillin-resistant S. aureus comparable to certain antibacterial drugs in use today.     

Fine-scale functional connectivity in somatosensory cortex revealed by high-resolution fMRI

High-resolution functional magnetic resonance imaging (fMRI) at high field (9.4 T) has been used to measure functional connectivity between subregions within the primary somatosensory (SI) cortex of the squirrel monkey brain. The hand-face region within the SI cortex of the squirrel monkey has been previously well mapped with functional imaging and electrophysiological and anatomical methods, and the orderly topographic map of the hand region is characterized by a lateral to medial representation of individual digits in four subregions of areas 3a, 3b, 1 and 2. With submillimeter resolution, we are able to detect not only the separate islands of activation corresponding to vibrotactile stimulations of single digits but also, in subsequent acquisitions, the degree of correlation between voxels within the SI cortex in the resting state. The results suggest that connectivity patterns are very similar to stimulus-driven distributions of activity and that connectivity varies on the scale of millimeters within the same primary region. Connectivity strength is not a reflection of global larger-scale changes in blood flow and is not directly dependent on distance between regions. Preliminary electrophysiological recordings agree well with the fMRI data. In human studies at 7 T, high-resolution fMRI may also be used to identify the same subregions and assess responses to sensory as well as painful stimuli, and to measure connectivity dynamically before and after such stimulations.     

Synthesis and structural characterization of binuclear palladium(II) complexes of salicylaldimine dithiosemicarbazones

A series of binuclear palladium(II) salicylaldiminato dithiosemicarbazone complexes have been synthesized and characterized. The palladium complexes were obtained by the reaction of various ethylene- and phenylene-bridged dithiosemicarbazones with Pd(PPh₃)₂Cl₂. The free salicylaldimine ligands and their palladium complexes were characterized by NMR and IR spectroscopies, ESI-mass spectrometry, elemental analyses and for two representative complexes also by X-ray diffraction. In both metal complexes, the solid-state structures show the two palladium centers to be coordinated in a slightly distorted square-planar geometry, which gives rise in each case to five- and six-membered chelate rings. The salicylaldimine thiosemicarbazone ligands coordinate to palladium in a tridentate manner, through the phenolic oxygen, imine nitrogen and thiolate sulfur atoms.     

Novel furan derivatives related to triphenylene: benzo[1,2-c:3,4-c′:5,6-c″]-trifuran,naphtho[1,2-c:3,4-c′]difuran and phenanthro[9,10-c]furan

The title compounds have been synthesised by sequences involving as the key step the trapping of arynes with furan.     

Asymmetric oxidation of achiral selenides to optically active selenoxides : Stereochemistry of the allyl selenoxide-selenenate [2,3] sigmatropic rearrangement

Asymmetric oxidation of methyl phenyl selenide ($\text{3}$), under anhydrous conditions, by chiral 2-sulfonyloxaziridines, $\text{1–2}$, gives optically active methyl phenyl selenoxide (8.1–9.3% ee). The stereochemistry of the selenoxide is determined by the configuration of the oxaziridine three membered ring with non-bonded steric interactions responsible for the chiral recognition. Asymmetric oxidation of E-phenyl cinnamyl selenide ($\text{7}$) by $\text{1–2}$ affords optically active l-phenylallyl alcohol ($\text{9}$). A concerted [2,3] sigmatropic rearrangement via an exo transition state is proposed.