Whole-field five-dimensional fluorescence microscopy combining lifetime and spectral resolution with optical sectioning

We report a novel whole-field three-dimensional fluorescence lifetime imaging microscope that incoporates multispectral imaging to provide five-dimensional (5-D) fluorescence microscopy. This instrument, which can acquire a 5-D data set in less than a minute, is based on potentially compact and inexpensive diode-pumped solid-state laser technology. We demonstrate that spectral discrimination as well as optical sectioning minimize artifacts in lifetime determination and illustrate how spectral discrimination improves the lifetime contrast of biological tissue.     

A Characterization of Minimal Legendrian Submanifolds in S2n+1

Let x: L ⁿ S²ⁿ⁺¹ R²ⁿ⁺² be a minimal submanifold in S²ⁿ⁺¹. In this note, we show that L is Legendrian if and only if for any A su(n + 1) the restriction to L of Ax, (–1)x satisfies f = 2(n + 1)f. In this case, 2(n + 1) is an eigenvalue of the Laplacian with multiplicity at least (n(n + 3)). Moreover if the multiplicity equals to ;(n(n + 3)), then L ⁿ is totally geodesic.     

Electrons and holes in undoped Nd2CuO4

Nd₂CuO_4±δ is the non-superconducting prototype of the Re_2−xM_xCuO₄t−y family (Re=Pr, Nd, Sm and M=Ceor Th) of n-type oxide superconductors. Four-probe DC conductivity, EMF in P(O₂) gradient, and thermopower measurements have been used to characterise its electric transport and defect structure between 300 and 900°C and between 5×10⁻⁴ and 1 atm oxygen partial pressure.

The results show that Nd₂CuO_4±δ can be oxygen under-stoichiometric (with n-type conductivity), near-stoichiometric, and over-stoichiometric (with p-type conductivity) in different T, P(O₂) ranges.     

Note on a Ramsey-Turán type problem

Solving a problem of Erdös the existence of a graph withn vertices,cn ² edges and withoutK(4) andK(3, 3, 3) is proved. It remains an open question whether all such graphs containK(2, 2, 2).     

Concept of multipole magnetic field rotation in ECRIS

The conventional type of magnetic well is formed by superposition of two types of magnetic field, axial bumpy field and radial multipole field. It is used to contain plasma that consists of neutrals, ions and electrons. These particles are in constant motion in the well and energetic electrons create plasma by violent collisions with neutrals and ions. The confined electrons are constantly heated by ECR technique in the presence of magnetic field. In this paper it has been shown theoretically that how the electron motion is influenced in terms of heating, containment and azimuthal uniformity of plasma, by the axial rotation of the multipole magnetic field [1,2]. Afterwards, the feasibility of achieving a rotating magnetic multipole field is discussed to some extent. And it is seen that it is not beyond the capability of the scientific community in the present scenario of the advanced technology. Presently, it can be achieved for lesser field and slightly larger size of the multipole electromagnet and can be used for improvement of the ECR ion source (ECRIS).     

Dynamics of slip band formation in fcc alloys

The problems induced by the inhomogeneity of deformation of alloys with high solute concentration are discussed using experimental results on Cu-2...10% Ni and Cu-30% Zn single crystals. Combining microscopic observations (etch-pit/stress-pulse method) with mesoscopic studies (microcinematography of slip line formation) and with macroscopic measurements (stress relaxation) in terms of the effective activation volumes, it is inferred that theories on the motion of a dislocation across the obstacle field in the slip plane can be compared with microscopic (etch-pit) results, while the macroscopic deformation kinetics and the critical resolved shear stress in the yield region of inhomogeneously deformed alloys might rather be controlled by the transfer process of slip to neighbouring slip planes.Fruitful discussions with Prof. Ch. Schwink and Dipl.-Phys. A. Hampel, as well as the continuous financial supports by the Deutsche Forschungsgemeinschaft, now in project A9 of SFB 319 are gratefully acknowledged.     

Une nouvelle preparation du fluoroacetylene - sa reaction avec les organometalliques. Synthese d'alcynes et d'enynes divers

FCCH has been prepared from 1,1-difluoroethylene at low temperature. Its reaction with various organometallics opens a way to acetylenes bearing tertiary alkyl-, vinyl-, aryl- or heteroaryl groups directly α to the unsaturation.     

Absolute configuration of eldanolide,the wing gland pheromone of the male African sugar cane borer,Eldana saccharina (Wlk.) syntheses of its (+) and (−) enantiomers.

Eldanolide $\text{1}$, a novel terpenoid lactone pheromone, was shown to have (3S,4R) configuration by synthesis of both enantiomers and comparison of their CD with the natural pheromone.     

Refractory methylated arsenic compounds in estuarine waters: Tracing back elusive species

Water from the Tagus estuary, Portugal, was concentrated and purified through evaporation, solvent extraction, ion exchange and HPLC, and peaks of refractory arsenicals were detected by difference between total arsenic (GF AA) and hydride-forming arsenic species (HG QF AA). DCI mass spectra of these fractions presented peaks at m/z 139, 157 and 159; the proportion of m/z 157 and 159 peaks, approx. 3:1, suggested a chlorinated moiety. DCI MS/MS daughter-ion fragmentation of these peaks seems compatible with dimethylarsenic (cacodylic) acid and structures of the type Me₂As(O)Cl or Me₃As(OH)F. The refractory character of these fractions, however, cannot be explained by these structures. Further work with mixtures of halogen and arsenic species injected in the HPLC system showed that fluoride and iodide can shift DMA (dimethylarsenic) and TMAO (trimethylarsine oxide) to shorter retention times but not to R_f values similar to refractory arsenicals. These latter are attained by mixtures of sodium chloride + arsenobetaine, and sodium fluoride and chloride + arsenocholine. We suggest that peaks at m/z 139 and 157 correspond to fragments of a heavier refractory molecule mainly formed by halogenated betaines including chloroarsenobetaine and chloro- and fluoro-arsenocholine.     

An analysis of the factors affecting the peak shape and the quantitative reliability of a heat flux DSC cell

In a previous work it was shown that unexpected problems may arise in the calibration of a heat flux DSC cell. To understand the origin of these problems an analysis has been undertaken of what happens in the cell before, during and after the peak. Here the first part of this analysis is reported dealing with the baseline and with the dependence of the recorded signal on time. Analytical expressions are obtained connecting the measured signal with experimental variables and instrument constants. Completely independent on sample related properties, a maximum measurable ΔT is introduced as limiting factor for quantitative reliability.