Characterization of the potential new phthalides in Ligusticum chuanxiong Hort. using ultra‐performance liquid chromatography coupled with quadrupole time of flight tandem mass spectrometry

The characterization of unknown compounds is still a great challenge currently. A strategy for deduction of potential new phthalides through the characterization of isomers based on ultra‐performance liquid chromatography coupled with quadrupole time of flight tandem mass spectrometry was proposed here to characterize the unknown compounds of Ligusticum chuanxiong Hort. (Chuanxiong). This proposed strategy consisted of four steps: (1) the high resolution MS data was collected, and the peaks were screened preliminarily by UNIFI^TM platform based on the in‐house database; (2) the fragmentation patterns and the characteristic fragments were summarized based on the representative standards; (3) the target compounds were identified based on the fragmentation rules, standards comparison and false positive exclusion; (4) the unknown components were structurally characterized according to the accurate mass and fragmentation patterns analysis. This strategy was successfully applied to the identification and deduction of phthalides in Chuanxiong. A total of 81 phthalides were detected. Fifty‐five known phthalides were identified, and 26 potential new phthalides were characterized. This research enriched the material basis of Chuanxiong, and provided a liquid chromatography tandem mass spectrometry‐oriented method for the discovery of the potential new compounds.     

IDENTIFICATION OF THE EXOPOLYSACCHARIDE AMYLOVORAN BY NMR[1]

Structural analysis of the exopolysaccharide (EPS) amylovoran produced by different natural Erwinia amylovora isolates revealed repeating pentasaccharide substructures substituted 30–40% with a sixth monosaccharide when isolated from host plants of the Malaceae species. Only a pentasaccharide substructure was found for pathogens isolated from Rubus plants. The differences between both substructures, obtained after treatment of the amylovorans with a depolymerase, were shown with NMR. The host range of fire blight bacteria could be partially found in this difference.     

Effect of DODAB Nano-Sized Cationic Bilayer Fragments against Leishmania amazonensis

The dioctadecyldimethylammonium bromide (DODAB) is a double-chained cationic lipid with potent bactericide and fungistatic activities; however, its toxicity on protozoan parasites is still unknown. Here, we show the antileishmanial activity of DODAB nano-sized cationic bilayer fragments on stationary-phase promastigotes and amastigotes of Leishmania amazonensis, the causative agent of cutaneous leishmaniasis. Upon treatment with DODAB, we analyzed the parasite surface zeta-potential, parasite viability, cellular structural modifications, and intracellular proliferation. The DODAB cytotoxic effect was dose-dependent, with a median effective concentration (EC₅₀) of 25 µM for both life-cycle stages, comparable to the reported data for bacteria and fungi. The treatment with DODAB changed the membrane zeta-potential from negative to positive, compromised the parasite’s morphology, affected the cell size regulation, caused a loss of intracellular organelles, and probably dysregulated the plasma membrane permeability without membrane disruption. Moreover, the parasites that survived after treatment induced small parasitophorous vacuoles and failed to proliferate inside macrophages. In conclusion, DODAB displayed antileishmanial activity, and it remains to be elucidated how DODAB acts on the protozoan membrane. Understanding this mechanism can provide insights into the development of new parasite-control strategies.     

Fragmentation of S nuclei in photoemulsion at 3.7 AGeV

Data on fragmentation of ³²S nuclei in emulsion at 3.7 AGeV are presented. The fragmentations are studied in terms of the impact parameter of collisions of the ³²S projectiles with the different target nuclei. The fragmentation cross sections and the multiplicities of the different fragments are nearly independent of the sulfur incident energy. The fragmentation of ³²S nuclei into alpha isotopes are extensively studied. The transverse momentum spectra of the emitted fragments are fitted by two Maxwell-Boltzmann distributions of different average transverse momenta. The characteristics (multiplicities and P_t-distributions) of the He-fragments produced in the central collisions are different from those emitted in the peripheral collisions.     

A new experimental approach for isochronous mass measurements of short-lived exotic nuclei with the FRS-ESR facility

Projectile fragments separated in flight with the FRS have been injected into the storage ring ESR. Operating the ESR in the isochronous mode has enabled high-resolution mass measurements of short-lived isotopes. Already in our pilot experiments the Isochronous Mass Spectrometry (IMS) has provided accurate results for a restricted isotope range in the neighborhood of a selected isotope characterized by the best isochronous condition. In the present experiment this restriction has been overcome by precise external magnetic rigidity determination (1.5·10^–4) at the dispersive midplane of the FRS. In this way the mass resolving power for neutron-rich fission fragments covering a large mass-over-charge ratio in one spectrum has been improved by up to one order of magnitude and the accuracy by more than a factor of two.     

A new technique for proving realisability and consistency theorems using finite paraconsistent models of cut‐free logic

A new technique for proving realisability results is presented, and is illustrated in detail for the simple case of arithmetic minus induction. CL is a Gentzen formulation of classical logic. CPQ is CL minus the Cut Rule. The basic proof theory and model theory of CPQ and CL is developed. For the semantics presented CPQ is a paraconsistent logic, i.e. there are non‐trivial CPQ models in which some sentences are both true and false. Two systems of arithmetic minus induction are introduced, CL‐A and CPQ‐A based on CL and CPQ, respectively. The realisability theorem for CPQ‐A is proved: It is shown constructively that to each theorem A of CPQ‐A there is a formula A *, a so‐called “realised disjunctive form of A ”, such that variables bound by essentially existential quantifiers in A * can be written as recursive functions of free variables and variables bound by essentially universal quantifiers. Realisability is then applied to prove the consistency of CL‐A, making use of certain finite non‐trivial inconsistent models of CPQ‐A. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Independence results for weak systems of intuitionistic arithmetic

This paper proves some independence results for weak fragments of Heyting arithmetic by using Kripke models. We present a necessary condition for linear Kripke models of arithmetical theories which are closed under the negative translation and use it to show that the union of the worlds in any linear Kripke model of HA satisfies PA. We construct a two‐node PA‐normal Kripke structure which does not force iΣ₂. We prove i?₁ ? i?₁, i?₁ ? i?₁, iΠ₂ ? iΣ₂ and iΣ₂ ? iΠ₂. We use Smorynski's operation Σ′ to show HA ? lΠ₁.     

60 A GeV16O原子核在核乳胶中的电磁离解

对60 A GeV16O在原子核乳胶中的电磁离解现象首次进行了高统计的研究,得到电磁离解截面随束流能量的增加而增加,射弹碎片电荷分布和200 A GeV16O在乳胶中电磁离解的电荷分布一致,但电荷为3≤Z≤5的射弹碎片的发射概率低于200 A GeV能区,这些特点和Weiszacker和Williams的经典电磁理论模型计算结果一致.60 A GeV16O电磁离解下各反应道出现的概率和200 A GeV能区结果基本一致,但同14.6 A GeV能区的结果不同,在60 A GeV能区16O电磁离解主要是由电偶及电四激发引起的巨偶极和巨四极共振及准氘核效应过程所致,这一点可以通过电磁离解下质子的多重数分布得到定性解释.电磁离解下α射弹碎片的分布同非弹核作用下α碎片的分布规律不同,说明α碎片的产生机制不同.     

AFM method for investigation of irradiated polymers

Tracks of swift heavy ions (Xe and Bi) at the surface of polymer (PET) were studied using AFM and surface defects—cavities (for Xe) and hillocks with cavities on its top (for Bi) were found. Thermal behavior of these Bi-irradiated samples (during annealing from 70°C to 180°C) was investigated. It was found that low-temperature annealing does not change the shape of surface defects, while high-temperature annealing leads to slow disappearance of these defects.

Irradiation of a stack of ultra-thin PET films by fission fragments was carried out and some sheets were then investigated separately. Two types of defects, corresponding to two main types of incident fragments (according to average energy distribution) were found. The deep structure of a track was studied and the ranges for two types of fragments were estimated. The increase of area of destruction was found at the depth 10–12 μm, which may be associated with changing of mechanism of interaction of passing particle with polymer and the dominant role of nuclear interaction. The obtained results are supported by a model calculation.     

Measurement of nanosize etched pits in SiO2 optical fiber conduit using AFM

Fission fragment tracks from ²⁵²Cf have been observed in SiO₂ optical fiber, using an atomic force microscope (AFM), after a very short chemical etching in hydrofluoric acid solution at normal temperature. The nuclear track starting and evolution process is followed by the AFM direct measurements on the material surface and beyond a fine layer of the surface material. The images of the scanned cones were determined observing the two predominant energies from ²⁵²Cf fission fragments and the development of the tracks in the 150 μm diameter optical fiber conduit.