CIRCADIAN PHASE OF SPARROWS: CONTROL BY LIGHT AND DARK

Abstract— Sparrows ( Passer domesticus ) are day-active birds which exhibit circadian rhythms of perch-hopping activity. The phases of sparrow's circadian rhythms were studied following single 4 h light pulses, single 4 h dark pulses, doublet treatments of light and dark pulses, and a 10 h light pulse.
The sparrows exhibited a phase response curve to 4 h light pulses with maximum phase advances (3.8 h) at CT20 and maximum phase delays(–1.3 h) at CT16. The sparrows also displayed a phase response curve to dark pulses with maximum phase advances (2.2 h) at CT16 and maximum phase delays at CTO(–0.7 h).
The remaining pulses were imposed during the subjective dark-time. The 10 h pulse beginning 1 h after lights-out produced a 2.2 h phase shift. The doublet of 2 h pulses that were the "skeleton" of the 10 h pulse produced a 2.5 h phase shift. The early 2 h pulse, applied by itself resulted in a -0.4 h delay; the late 2 h pulse applied singly produced a 3.1 h advance. When an early 3 h dark pulse was imposed together with a late light pulse, the phase was advanced 3.6 h; singly the pulses produced 1.8 h and 2.7 h advances.     

Triplet states in 1,3-butadiene

The electron impact excitation spectrum 0f 1,3-butadiene has been studied at 20, 35 and 55 eV impact energies and scattering angles of 10° to 80°. Two low lying states are observed with maxima at 3.2 and 4.9 eV, and are identified as the ³B_u state and ³A_g state respectively     

Syn and Anti Isomer Preference in Oximes: An Undergraduate Organic Chemistry Experiment

An experiment is described that links a nucleophilic carbonyl addition reaction to a study of structure–activity relationships. Students prepare a series of oximes (from readily available ketones and aldehydes) and, with the use of NMR, define the ratio of syn and anti isomers formed in the reaction. From these data, a quantitative assessment of the steric hindrance of hydrogen, methyl, ethyl, isopropyl, and t–butyl can be obtained.     

Synthesis of 3,5-Disubstituted-4,5-dihydroindeno[1,2-c] [1,2]diazepin-6(1H)-ones

3,5-Disubstituted 4,5-dihydroindeno[1,2-c][1,2]diazepin-6 (1H)-ones ( 3a–g ) were obtained in 29–72% yields by condensing 2-(substituted-2-acylethyl)-1,3-indandiones ( 1a–n ) with hydrazine. The NH group of the indenodiazepinones 3a–g is quite unreactive. Two methods based on the Michael reaction were used for preparing the acylethylindandiones 1a–n : one from 1,3-indandione and chalcone-type compounds and the other from 2-benzylidene-1,3-indandione and acetophenones. The latter method was found more practical and of more general application.     

Synthesis,Structure and Reactivity of Organoindium 1,2-Benzenedithiolates and 2-Amidobenzenethiolates

Organoindium compounds of redox active 1,2-benzenedithiolate and 2-amidobenzenethiolate ligands were synthesized and tested for reactivity against mild oxidants. The reaction of Me₃In and (NCN)InMe₂ [NCN=2,6-bis(dimethylaminomethy)phenyl] with 3,4-toluenedithiol (H₂tdt) at room temperature afforded [MeIn(tdt)(py)]₂ ( 1 ) and (NCN)In(tdt) ( 2 ), respectively. A similar reaction of Me₃In with 2-aminobenzenethiol (H₂abt) in toluene under reflux afforded [MeIn(abt)(py)]₂ ( 3 ). The reaction of (NCN)InCl₂ with one equivalent of Li₂(abt) or two equivalents of Li(Habt) afforded the compounds [(NCN)In(abt)]⋅LiCl(thf)₂ ( 4 ⋅LiCl(thf)₂) and (NCN)In(Habt)₂ ( 5 ), respectively. The X-ray crystal structures of 1 and 3 are similar and show dimeric structures via μ-S-(tdt) and μ-N-(abt) ligands, respectively. Compounds 2 and 4 possess similar monomeric structures and tridentate NCN pincer ligands. DFT computational studies have been used to rationalize the observed solid-state structures and discern the potential reactivity of compounds 1 – 4 against oxidants. The reaction of 1 and 2 with excess iodine resulted in loss of the 3,4-toluenedithiolate ligand and the formation of the oligomeric disulfide [tdt]_n, while 3 and 4 showed no reactivity under similar conditions. This contrasts the reactivity of previously reported organoindium o-amidophenolate complexes which undergo oxidative addition of iodine to afford ligand-centered radical species.