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.     

The 61/2+ yrast isomer in149Tb

An isomeric state (T _1/2=4.0±0.2ns, E ^*=9.915 MeV,I _π=61/2⁺)has been found in ¹⁴⁹ Tb by measuring the half-life of the K internal conversion line of the 184 keV E2 deexciting transition. The breaking of the neutron core is theoretically expected at that spin resulting in sizeable increase of the oblate deformation.     

Pressure field,vorticity field,and coherent structures in two-dimensional incompressible turbulent flows

Geometrical arguments lead to the definition of two education criteria for coherent structures in two-dimensional incompressible turbulent flows. These criteria involve the pressure or the vorticity field and are compared.     

The 20Ne(12C,p)31P, 20Ne(12C,d)30P and 20Ne(12C, α)28Si reactions in the region of the coulomb barrier

The excitation functions of the ²⁰Ne(¹²C, p)³¹P, ²⁰Ne(¹²C, d)³⁰P. and ²⁰Ne(¹²C, α)²⁸ Si reactions were measured at bombarding energies between 6.9 and 16.9 MeV (c.m.) by steps of 156 keV, at an average lab angle of 2.82°. The average coherence width of states in the compound nucleus, ³²S, populated in the reactions was deduced through the analysis of the fluctuations in the measured excitation functions. The result agrees with the average compound nucleus width predicted by the Hauser-Feshbach expression. The fluctuation analysis shows that these reactions proceed mainly through the formation of a compound nucleus. A cross correlation analysis revealed that the fluctuations in the different excitation functions are statistically independent and that there is no evidence of intermediate structure resonances.     

The mixed Hodge–Riemann bilinear relations for compact Kähler manifolds

We prove the Hodge–Riemann bilinear relations, the hard Lefschetz theorem and the Lefschetz decomposition for compact K?hler manifolds in the mixed situation. Dedicated to Professor Henri Skoda on the occasion of his 60th birthday Received: February 2005; Revision: March 2005; Accepted: April 2005     

A New Class of Two‐Layer Green–Naghdi Systems with Improved Frequency Dispersion

We introduce a new class of Green–Naghdi type models for the propagation of internal waves between two (1 + 1)‐dimensional layers of homogeneous, immiscible, ideal, incompressible, and irrotational fluids, vertically delimited by a flat bottom and a rigid lid. These models are tailored to improve the frequency dispersion of the original bi‐layer Green–Naghdi model, and in particular to manage high‐frequency Kelvin–Helmholtz instabilities, while maintaining its precision in the sense of consistency. Our models preserve the Hamiltonian structure, symmetry groups, and conserved quantities of the original model. We provide a rigorous justification of a class of our models thanks to consistency, well‐posedness, and stability results. These results apply in particular to the original Green–Naghdi model as well as to the Saint–Venant (hydrostatic shallow water) system with surface tension.     

Astaxanthinogenesis in the yeastPhaffia rhodozyma

Astaxanthin is a diketo-dihydroxy-carotenoid produced byPhaffia rhodozyma, a basidiomicetous yeast. A low-cost fermentation medium consisting of raw sugarcane juice and urea was developed to exploit the active sucrolytic/urelolytic enzyme apparatus inherent to the yeast. As compared to the beneficial effect of 0.1 g% urea, a ready nitrogen source, mild phosphoric pre inversion of juice sucrose to glucose and fructose, promptly fermentable carbon sources, resulted in smaller benefits. Corn steep liquor (CSL) was found to be a valuable supplement for both yeast biomass yield (9.2 g dry cells/L) and astaxanthin production (1.3 mg/g cells). Distillery effluent (vinace), despite only a slightly positive effect on yeast growth, allowed for the highest pigment productivity (1.9 mg/g cells). Trace amounts of Ni² (1 mg/L, as a cofactor for urease) resulted in controversial effects, namely, biomass decrease and astaxanthin increase, with no effect on the release (and uptake) of ammonium ion from urea. Since the synthesized astaxanthin is associated with the yeast cell and the pigment requires facilitated release for aquaculture uses (farmed fish meat staining), an investigation of the yeast cell wall was undertaken using detergent-treated cells. The composition of the rigid yeast envelope was found to be heterogeneous. Its partial acid or enzymatic depolymerization revealed glucose and xylose as common monomeric units of the cell-wall glycopolymers. Yeast cell-wall partial depolymerization with appropriate hydrolases may improve the pigment bioavailability for captive aquatic species and poultry.