Biodetermination of N-(deacetyl-O-4-vinblastoyl-23)-L-tryptophan, a metabolite of vintriptol, by high-performance liquid chromatography with fluorescence detection.

The determination of N-(deacetyl-O-4-vinblastoyl-23)-L-tryptophan (vintriptol acid, VtrpA), a metabolite of the investigational semi-synthetic vinca alkaloid vintriptol [N-(deacetyl-O-4-vinblastoyl-23)-L-ethyltryptophan, VtrpE], in plasma and urine samples is described. Sample pretreatment included liquid-liquid extraction of the buffered (pH 5.0) biological samples with chloroform-2-propanol (95:5, v/v). The analyses were performed by ion-exchange high-performance liquid chromatography on normal-phase silica with fluorescence detection. The assay was applied to the analysis of samples from cancer patients who had been treated with VtrpE in a phase I clinical study. VtrpA was found to be a principal metabolite of VtrpE with up to 1.2% of the administered dose excreted in the urine.     

Are quasicrystals hume-rothery alloys?

In 1926 Hume Rothery discovered that for some simple alloys the electron to atom ratio e/a is a stability determining factor. We applied this energy band effect or Hume-Rothery rule to the quasicrystalline series Al₈₀Mn_20-xFe_x. The isomer shift of the Mössbauer spectra shows a maximum at x=9, where e/a=1.76. This strongly indicates a relatively low s-electron density, in agreement with the energy band effect.     

An alternatively spliced form of Met receptor is tumorigenic

The Met tyrosine kinase receptor is a widely expressed molecule, which mediates pleiotropic cellular responses following activation by its ligand, hepatocyte growth factor/scatter factor (HGF/SF). Previously, one of the authors identified an alternatively spliced form of Met (Met-SM) that lacked a single exon of a 47-amino-acid segment in the juxtamembrane domain. Here we report that Met-SM is a potent transforming gene in NIH3T3 mouse fibroblast cells. Met-SM-transfected NIH3T3 cells show stronger foci-forming activity than wild type- Met-transfected ones. In addition, Met-SM-transfected NIH3T3 cells form colonies in soft agar and are tumorigenic in athymic nu/nu mice. Furthermore, HGF/SF significantly increases the focus-forming activity of Met-SM comparing to wild type Met. The amount of protein and of tyrosine kinase activity of Met-SM accumulates to a high level following HGF/SF treatment. The accumulation of Met-SM correlated well with its delayed ubiquitination and increased stability. These results are consistent with the important role of the juxtamembrane domain in protein stability of Met receptor and suggest that the alternatively-spliced form may contribute to the development and progression of human cancer.     

Start-up of multi-species anaerobic digestion systems: extrapolation of the single species approach

This paper presents a brief evaluation of a start-up strategy for multi-species anaerobic digestion systems modelled as two-step reaction systems, where acidogenesis is described by Monod kinetics while the methanogenesis is described by Haldane kinetics. The start-up policy has been developed originally for single species systems with the aim of maximizing the biogas outflow rate. It consists of switching the dilution rate from minimum to maximum and then to the optimal value (bang-bang control) in order to bring the system from an arbitrary initial condition to the optimal set-point. This start-up strategy is applied to the multi-species system using an averaged model, which is usually the only model that can be identified for a multi-species system, as measuring individual biomasses is almost impossible in practice. Even the development of an accurate averaged model, fully characterizing the system dynamics based on the variation of the species proportions is difficult. The averaged models used in this study are built based on a more or less accurate knowledge of the species proportions and their kinetics at the start-up instant and used as such in the application of the start-up policy. It is shown that the start-up policy leads to an efficient ecosystem, characterized by high outflow rate of biogas, which is very close to the maximum even in the case of an inaccurate averaged model. The influence of the model accuracy on the system stability and its productivity is discussed. This study can also be viewed as a robustness evaluation with respect to model inaccuracy of the single species start-up strategy, as the process changes from the averaged kinetics to the kinetics of the winning species during species selection.     

On the derivation of simple dynamic models of anaerobic digestion using macroscopic bioreaction schemes

In this study, the problem of developing simple dynamic models of an anaerobic digestion process is tackled using an identification procedure which proceeds in several consecutive steps. Starting from sets of experimental data describing the time evolution of several key component concentrations, i.e. biomass(es), substrates and products, the minimal number of macroscopic bioreactions required to represent the data at hand, as well as the parameters of the associated stoichiometry matrix, are determined using maximum likelihood principal component analysis. Then, the structure of the kinetic laws, together with their parameters, are identified using likelihood ratio tests to navigate through the branches of decision trees made of various kinetic structures. The effectiveness of the modelling procedure is illustrated with a simulated example of anaerobic digestion. As usual sensors only provide aggregate measurements of the component concentration, a deeper investigation of practical identifiability is achieved in relation with the influence of measurement errors.     

A system of real quaternion matrix equations with applications

Let H be the real quaternion algebra and H^n×m denote the set of all n×m matrices over H. Let P∈H^n×n and Q∈H^m×m be involutions, i.e., P²=I,Q²=I. A matrix A∈H^n×m is said to be (P,Q)-symmetric if A=PAQ. This paper studies the system of linear real quaternion matrix equations

     

(E,E)‐2,5‐Diprop­oxy‐1,4‐bis­[2‐(2,4,6‐trimethoxy­phen­yl)ethen­yl]benzene

The title compound, C₃₀H₃₄O₈, crystallizes in the space group P with one‐half of a mol­ecule in the asymmetric unit. A three‐dimensional network is generated by OCH₃⋯π and CH⋯π inter­actions. The conformation of the C—C bond exocyclic to the central benzene ring is different from that of every other known derivative. A comparison of the geometry of the title mol­ecule and of its solid‐state structure with other 2,4,6‐trimeth­oxy‐substituted PPV [i.e. poly(p‐phenylenevinylene)] oligomers, in particular the isoprop­oxy‐substituted compound, is provided.     

The study of the (α, α′ f) reaction at 120 MeV on 232Th and 238U: (II). Fission barrier properties deduced from fission probabilities and angular distributions

The fission probabilities and angular distributions of the fission fragments for the (α, α'f) reaction on ²³²Th and ²³⁸U at a bombarding energy of 120 MeV have been measured from about 4 to 14 MeV excitation energy. Evidence for sub-barrier resonances has been found, the negativeparity ones occurring at the same excitation energy where photofission resonances have been observed. The data are analyzed with the two-humped barrier model. For ²³⁸U the data are reasonably well fitted with barriers similar to those known from the literature. For ²³²Th though, the outer barrier parameters are quite different: the height E_B = 6.6 MeV and the width (khω)_B = 1.2 MeV. Also for ²³²Th, introducing an additional mass symmetric and axially asymmetric outer barrier, as was previously found necessary for ²³⁸U, does not result in a good fit to the data at higher excitation energies.     

γ-decay of the deeply-bound hole states in 101Pd, 105Pd, 107Pd, 111Sn, 117Sn observed in the (3He, αγ) reaction at 70 MeV

The γ-decay of deep-hole states in ^{101, 105, 107}Pd was studied via the (³He, αγ) reaction at E_³he = 70 MeV and supplemented by data from ^{112, 118}Sn targets to investigate the deep-hole spreading mechanism. The γ-decay pattern for the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ deep-hole state shows a strong dependence on the spreading width: if the deep-hole state is observed as a sharp peak, it mainly decays to the low-lying $\text{7}\text{2}{}^{\mathrm{+}}$ state by a spin-flip M1 transition with a large M1-E2 mixing ratio; if the deep-hole state is observed as a broad bump, it decays statistically indicating the complete spreading of the hole strength over the underlying states; if the deep-hole state is observed with a structure intermediate between a sharp peak and broad bump, its γ-decay shows both decay patterns.A sharp peak at E_x = 2.396 MeV in ¹⁰¹Pd which carries a large fraction of the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ hole strength (C²S = 2.0) was found to be a single state having a width of less than 2.5 keV.For the spin-flip M1 transition the destructive interference between the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ component and the coupled components of the deep-hole state was found in heavily spread states.A quasiparticle-plus-rotor (QPR) model was applied to calculate the fragmentation in the doorway stage for the $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ neutron deep-hole state in the Pd isotopes. A reasonable agreement between the calculation and the experimental results was obtained for the strength fragmentation, for the nucleus ¹⁰¹Pd. However, the large M1-E2 mixing ratio experimentally observed was not reproduced.     

Isomer shift in binary iron alloys

The isomer shift of binary iron alloys is related to the itineracy of the valence electrons. The problem of a volume correction in disordered alloys is discussed and further avoided by using data of intermetallic compounds. From a large selection of possible parameters a linear combination of the electronegativityφ ^* and the electron densityn _ws in the Wigner-Seitz cell seems to be a good choice for fitting the data. The problem that these parameters are of minor importance for the cohesion in transition metal alloys is discussed.