Phototaxis in Euglena. V. Photosuppression of phototactic activity by blue light

Abstract— The phototactic response of Euglena gracilis is suppressed when the organisms are exposed to bright light of wavelength less than 650 nm. Activity returns in the dark, approximately 40 min being required for full restoration. Action spectral measurements demonstrate that the receptor pigment which mediates the suppression response may be a flavoprotein. Evidence is presented which indicates that photosuppression involves a direct action on the photo-tactic apparatus, perhaps a photobleaching of the tactic photoreceptor pigment.     

Synthesis and molecular structure of [Al(CH3)2]2[C10H22N4] [Al(CH3)3]2: Condensation product of trimethylaluminum and a multidentate open-chain amine

The crystalline condensation product [Al(CH₃)₂]₂[C₁₀H₂₂N₄][Al(CH₃)₃]₂ is prepared from reaction of the multidentate open-chain amine 1,4-bis(3-aminopropyl)piperazine with trimethylaluminum in methylene chloride. The compound crystallized in the monoclinic space groupC2/c with unit cell parametersa=25.166(12),b=7.268(4),c=17.316(4) Å,=115.3(4)°, andD _c =1.06 g cm^–3 forZ=4. Least-squares refinement based on 1054 observed reflections with intensitiesI 3(I) in the range 2<2<45° led to a finalR factor of 0.053 (R _w =0.064). The title compound resides on a crystallographic center of symmetry with independent Al-N distances of 1.889(5), 2.058(5), and 2.030(5) Å.     

Crystal and Molecular Structures of C6H5CH2SOCH2CONHCH2C6H5 and C6H5SOCH2CON(iC3H7)2

Abstract  The crystal structures for two of the ligands C₆H₅CH₂SOCH₂CONHCH₂C₆H₅ (1) and C₆H₅SOCH₂CON(ⁱC₃H₇)₂ (2) have been determined by X-ray diffraction. These compounds crystallize in orthorhombic system with space groups and cell parameters, Pca21(no. 29), a = 8.4600(5) ?, b = 5.3534(5) ?, c = 32.136(2) ?, V = 1455.42(15) ?³ and Pna21(no. 33) a = 17.5563(11) ?, b = 5.7902(4) ?, c = 14.2866(9) ?, V = 1452.30(16) ?³, respectively. These molecules are stabilized in solid state by various intra and intermolecular hydrogen bonding interactions to give polymeric structures. The reported IR spectra of these compounds in solid state could be explained on the basis of the observed intermolecular hydrogen bonding interactions. Index Abstract  The title compounds C₆H₅CH₂SOCH₂CONHCH₂C₆H₅ (1) and C₆H₅SOCH₂CON(ⁱC₃H₇)₂ (2) were prepared by the oxidation of corresponding sulfides with H₂O₂/SeO₂ in methanol and their structures were determined. The structures show that the SO and CO groups are having “anti” configuration in 1 and “syn” configuration in 2. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

On the origin of optical absorptions in heavy metal fluoride glass: I. The absorption at 2.9 μm

We present a comparison of IR absorption spectra for heavy metal flouride glass processed either in a HF or H₂O atmosphere. The similarities are remarkable for the 2.9-μm absorption features, which precisely coincide in peak wave length, line shape, and line width for both treatment methods. A discussion and an analysis of these findings are given.     

Batch versus Flow Photochemistry: A Revealing Comparison of Yield and Productivity

The use of flow photochemistry and its apparent superiority over batch has been reported by a number of groups in recent years. To rigorously determine whether flow does indeed have an advantage over batch, a broad range of synthetic photochemical transformations were optimized in both reactor modes and their yields and productivities compared. Surprisingly, yields were essentially identical in all comparative cases. Even more revealing was the observation that the productivity of flow reactors varied very little to that of their batch counterparts when the key reaction parameters were matched. Those with a single layer of fluorinated ethylene propylene (FEP) had an average productivity 20 % lower than that of batch, whereas three‐layer reactors were 20 % more productive. Finally, the utility of flow chemistry was demonstrated in the scale‐up of the ring‐opening reaction of a potentially explosive [1.1.1] propellane with butane‐2,3‐dione.     

Application of the quasi-variational coupled cluster method to the nonlinear optical properties of model hydrogen systems

We present a pilot application of the recently proposed quasi-variational coupled cluster method to the energies, polarizabilities, and second hyperpolarizabilities of model hydrogen chains. Relative to other single-reference methods of equivalent computational complexity, we demonstrate this method to be highly robust and especially useful when traditional coupled cluster theory fails to perform adequately. In particular, our results indicate it to be a suitable method for the black-box treatment of multiradicals, making it of widespread general interest and applicability.     

cis,cis,cis‐Tetra­methyl 1,2,4,5‐cyclo­hexane­tetra­carboxyl­ate

The title compound, C₁₄H₂₀O₈, was synthesized from the hydrogenation of tetra­methyl 1,4‐cyclo­hexa­diene‐1,2,4,5‐tetra­carboxyl­ate with a catalytic amount of palladium/carbon. All four carbonyl moieties of the methyl ester groups are on the same face of the chair‐conformed ring. The substantial ring distortion associated with the 1,3‐diaxial methoxycarbonyl substituents is reflected in the large difference between bond angles as well as torsion angles, respectively, that in undistorted cyclo­hexanes would be approximately the same.     

Oxidative cyclization and fragmentation of steroidal alcohols induced by ceric ammonium nitrate

Oxidative cyclizations of steroidal alcohols (1a–1d) using ceric ammonium nitrate (CAN) in aqueous acetonitrile or aqueous acetic acid gave the corresponding cyclic ethers (2a–2d), whereas the tertiary alcohol (4) gave secosteroid (5).     

Angular Averaged Profiling of the Radial Electric Field in Compensated FTICR Cells

A recent publication from this laboratory reported a theoretical analysis comparing approaches for creating harmonic ICR cells. We considered two examples of static segmented cells--namely, a seven segment cell developed in this laboratory and one described by Rempel et al., along with a recently described dynamically harmonized cell by Boldin and Nikolaev. This conceptual design for a dynamically harmonized cell has now been reduced to practice and first experimental results obtained with this cell were recently reported in this journal; this publication reported details of cell construction and described its performance in a 7 tesla Fourier transform mass spectrometer. We describe the extension of theoretical analysis creating harmonic ICR cells to include angular-averaged radial electric field calculations and a discussion of the influence of trapping plates.     

A microfluidic device for whole-animal drug screening using electrophysiological measures in the nematode C. elegans

This paper describes the fabrication and use of a microfluidic device for performing whole-animal chemical screens using non-invasive electrophysiological readouts of neuromuscular function in the nematode worm, C. elegans. The device consists of an array of microchannels to which electrodes are attached to form recording modules capable of detecting the electrical activity of the pharynx, a heart-like neuromuscular organ involved in feeding. The array is coupled to a tree-like arrangement of distribution channels that automatically delivers one nematode to each recording module. The same channels are then used to perfuse the recording modules with test solutions while recording the electropharyngeogram (EPG) from each worm with sufficient sensitivity to detect each pharyngeal contraction. The device accurately reported the acute effects of known anthelmintics (anti-nematode drugs) and also correctly distinguished a specific drug-resistant mutant strain of C. elegans from wild type. The approach described here is readily adaptable to parasitic species for the identification of novel anthelmintics. It is also applicable in toxicology and drug discovery programs for human metabolic and degenerative diseases for which C. elegans is used as a model.