Cytotoxic diterpenoids from Vietnamese medicinal plant Croton tonkinensis GAGNEP

Six new ent-kaurane-type diterpenoids were isolated from the leaves of the endemic Vietnamese medicinal plant Croton tonkinensis GAGNEP. (Euphorbiaceae) together with three known ent-11alpha-acetoxy-7beta,14alpha-dihydroxykaur-16-en-15-one (1), ent-kaur-16-en-15-one 18-oic acid (5) and ent-18-hydroxykaur-16-ene (7). Their structures were determined by spectroscopic analyses to be ent-7beta-acetoxy-11alpha-hydroxykaur-16-en-15-one (2), ent-18-acetoxy-11alpha-hydroxykaur-16-en-15-one (3), ent-11alpha-acetoxykaur-16-en-18-oic acid (4), ent-15alpha,18-dihydroxykaur-16-ene (6), ent-11alpha,18-diacetoxy-7beta-hydroxykaur-16-en-15-one (8), and ent-(16S)-1alpha,14alpha-diacetoxy-7beta-hydroxy-17-methoxykauran-15-one (14). ent-Kaurane-type diterpenoids from Croton tonkinensis 2-4, 6, and 9-13, were tested for toxicity in the brine shrimp lethality assay. Compounds 9, 10, and 12 demonstrated significant activity, compounds 2, 3, 6, and 11 showed weak activity, and compounds 4 and 13 were inactive.     

Fast determination of the tin content in cassiterite ores by photon activation method

Photon activation analysis has been success-fully applied to the fast and non-destructive analysis of tin in cassiterite ores based on the 159.7 keV gamma line of^123mSn produced in the¹²⁴Sn/γ, n/^123mSn reaction. In order to improve the accuracy of analytical results, corrections for self-absorption and pile-up effects were performed. Under typical conditions /15 μA electron beam current, 15 MeV bremsstrahlung energy, 5 min irradiation time and 10 min measurement/ the sensitivity of the analysis is 10 ppm. The proposed method can be used for routine analysis of tin in geological samples.     

Detection of chlorinated quinones using interdigitated electrodes coupled with capillary electrophoresis

An array of eight interdigitated microband gold electrodes (IDEs) has been developed together with electrophoretic separation for analysis of chlorinated hydroquinones (ClHQs) and benzoquinones (ClBQs). The IDE chip positioned very close to the separation capillary outlet served as an amplification/detection system without the requirement for frequent "capillary-electrode" alignment. ClHQs, electrophoretically migrating to the IDE surface, were oxidized at +1.1 V by seven electrodes of the array and then detected by the remaining electrode, poised at -0.1 V. Conversely, ClBQs were detected at +1.1 V by the detecting electrode after having been reduced at the 7 adjacent electrodes poised at -0.1 V. There was an amplification effect on both the detecting electrode as well as the adjacent electrodes because of the recycle between ClHQs and ClBQs. The detecting "amplification" current response was dependent on the potentials applied, the position of the detecting electrode on the array, the number of adjacent electrodes being used for recycling and the distance between the oxidative and reductive electrodes. Micellar electrokinetic chromatography (MEKC) separation of the analytes was achieved using 30 mM sodium dodecyl sulfate (SDS) with a detection limit in the range of 2-20 micro M. In addition to a facile "capillary-electrode" alignment, the important aspect described here was the capability of detecting through recycling a reduced compound (in the case of ClHQs) at a negative potential to circumvent fouling and electroactive interferences. An appealing feature was also the concurrent oxidation/reduction detection for each compound to ascertain peak assignment, as interfering compounds are less likely to exhibit the same oxidative/reductive characteristics and electrophoretic mobilities as the target analytes.     

Contribution à la phytochimie du genre Gentiana. XXVI.. Identification d'une nouvelle di-O-glucosyl cinnamoyl-C-glucosylflavone extraite des feuilles de Gentiana X marcailhouana RY.

Phytochemistry of Genus Gentiana. XXVI. Identification of a New Di-O-glucosyl Cinnamoyl-C-glucosylflavone in the Leaves of Gentiana X marcailhouana RY . A new di-O-glucosyl cinnamoyl-C-glucosylflavone has been identified as 4′-O-β-D -glucosyl-2″-O-[2-O-β-D -glucosyl-2,4,5-trihydroxy-(E)-cinnamoyl]isoorientin ( 1 ).     

Contribution à la phytochimie du genre Gentiana. XXV. Etude des composés flavoniques et xanthoniques dans les feuilles de Gentiana X marcailhouana RY. Nouveaux cinnamoyl-C-glucosides flavoniques

Phytochemistry of genus Gentiana XXV: Study of the flavonic and xanthonic compounds in leaves of Gentiana X marcailhouana RY . New cinnamoyl-C-glucosyl-flavones Nine flavonic compounds: isoorientin ( 1 ), isovitexin ( 2 ), isoorientin-4′-O-β-D -glucoside ( 3 ), isovitexin-4′-O-β-D -glucoside ( 4 ), luteolin-7-O-β-D -glucoside ( 5 ), trans-cafeoyl-2′′-isoorientin ( 6 ), trans-feruloyl-2′′-isoorientin ( 7 ), trans-p-coumaroyl-2′′-isoorientin ( 8 ), p-O-β-D -glucosyl-trans-cafeoyl-2′′-isoorientin ( 9 ) and three xanthones: gentioside ( 10 ), isogentisine ( 11 ), mangiferin ( 12 ), have been identified from leaves of Gentiana X marcailhouana RY . Compounds 8 and 9 were described for the first time. The cyclitol L -(+)-bornesitol ( 13 ) has been also isolated.     

Transition state dynamics of the OH + H2O hydrogen exchange reaction studied by dissociative photodetachment of H3O2-

Dynamics in the transition state region of the bimolecular OH + H2O-->H2O + OH hydrogen exchange reaction have been studied by photoelectron-photofragment coincidence spectroscopy of the H3O2- negative ion and its deuterated analog D3O2-. The data reveal vibrationally resolved product translational energy distributions. The total translational energy distribution shows a vibrational progression indicating excitation of the antisymmetric stretch of the water product. Electronic structure calculations at the QCISD level of theory support this analysis. Examination of the translational energy release between the neutral products reveals a dependence on the product vibrational state. These data should provide a critical test of ab initio potential energy surfaces and dynamics calculations.     

Regularity of weak solutions to rate‐independent systems in one‐dimension

We show that under some appropriate assumptions, every weak solution (e.g. energetic solution) to a given rate‐independent system is of class SBV, or has finite jumps, or is even piecewise C¹. Our assumption is essentially imposed on the energy functional, but not convexity is required.     

Robust energy planning in buildings with energy and comfort costs

Energy management in buildings is addressed in this paper. The energetic impact of buildings in the current energetic context is first depicted. Then the studied optimization problem is defined as the optimal management of production and consumption activities in houses. A scheduling problem is identified to adjust the energy consumption to both the energy cost and the inhabitant’s comfort. The available flexibilities of the services provided by domestic appliances are used to compute optimal energy plans. These flexibilities are associated to time windows or heating storage abilities. A constraints formulation of the energy allocation problem is given. A derived mixed linear program is used to solve this problem. The energy consumption in houses is very dependent to uncertain data such as weather forecasts and inhabitants’ activities. Parametric uncertainties are introduced in the home energy management problem in order to provide robust energy allocation. Robust linear programming is implemented. Event related uncertainties are also addressed through stochastic programming in order to take into account the inhabitant’s activities. A scenario based approach is implemented to face this robust optimization problem.     

A Boat-Shaped Tetracationic Macrocycle with a Semiconducting Organic Framework

We report the synthesis of a tetracationic macrocycle which contains two N,N′-bis(methylene)naphthalenediimide units inserted in between the pyridinium rings of the bipyridinium units in cyclobis(paraquat-p-phenylene) (CBPQT⁴⁺ or “blue box”) and describe the investigation of its potential use in materials for organic electronics. The incorporation of the two naphthalenediimide (NDI) units into the constitution of CBPQT⁴⁺, not only changes the supramolecular properties of the tetracation in the solid state, but also has a profound influence on the electrochemical and electronic behavior of the resulting tetracationic macrocycle. In particular, the solid-state (super)structure, investigated by single-crystal X-ray diffraction, reveals the formation of a three-dimensional (3D) supramolecular framework with ca. 2.8 nm diameter one-dimensional (1D) hexagonal channels. Electrochemical studies on solid-state thin films of the macrocycle show that they exhibit semiconducting properties with a redox-conductivity of up to 7.6×10⁻⁴ S m⁻¹. Moreover, EPR and ENDOR spectroscopies show that charge is equally shared between the NDIs within the one-electron reduced state of the NDI-based macrocycle on the time scale of these techniques.