Theoretical study on properties of new isotope (265)Bh

The properties of nuclei belonging to the newly observed a-decay chain starting from (265)Bh have been studied. The axially deformed relativistic mean-field calculation with the force NL-Z2 has been performed in the blocked BCS approximation. Some ground state properties such as binding energies, deformations, spins, and parities, as well as Q-values of the alpha-decay for this decay chain have been calculated and compared with known experimental data. Good agreement is found. The single-particle spectrum of the nucleus (265)Bh is studied and some new magic numbers are found, while the magnitudes of the shell gaps in superheavy nuclei are much smaller than those of nuclei before the actinium region, and the Fermi surfaces are close to the continuum. Thus the superheavy nuclei are usually not stable. The alpha-decay lifetimes in the (265)Bh decay chain are evaluated by different formulae, and compared with experimental data. The methods which give good agreement with the data are selected.

Systematic study of properties of Hs nuclei

The ground-state properties of Hs nuclei are studied in the framework of the relativistic meanfield theory. We find that the more relatively stable isotopes are located on the proton abundant side of the isotopic chain. The last stable nucleus near the proton drip line is probably the (255)Hs nucleus. The alpha-decay half-lives of Hs nuclei are predicted, and together with the evaluation of the spontaneous-fission half-lives it is shown that the nuclei, which are possibly stable against spontaneous fission are (263-274)Hs. This is in coincidence with the larger binding energies per nucleon. If (271-274)Hs can be synthesized and identified, only those nuclei from the upper Z = 118 isotopic chain, which are lighter than the nucleus (294)118, and those nuclei in the corresponding alpha-decay chain lead to Hs nuclei. The most stable unknown Hs nucleus is (268)Hs. The density-dependent delta interaction pairing is used to improve the BCS pairing correction, which results in more reasonable single-particle energy level distributions and nucleon occupation probabilities. It is shown that the properties of nuclei in the superheavy region can be described with this interaction.

Transient state of chiral recognition in a binary mixture of cyclodextrins in capillary electrophoresis

The transient state (as the defined point where no enantioseparation is obtained in a dual chiral selector system) of chiral recognition of aminoglutethimide in a binary mixture of neutral cyclodextrins (CDs) was studied by capillary electrophoresis (CE). The following three dual selector systems were used: alpha-cyclodextrin (alpha-CD) and beta-cyclodextrin (beta-CD); alpha-CD and heptakis(di-O-methyl-beta-cyclodextrin) (DM-beta-CD); alpha-CD and heptakis(tri-O-methyl-beta-cyclodextrin) (TM-beta-CD). The S-(-) enantiomer of the analyte was more strongly retained in the presence of either alpha-CD or TM-beta-CD at pH 2.5, 100 mM phosphate buffer, while the R-(+) enantiomer was more strongly retained in the presence of either P-CD or DM-P-CD. In the more simple case, the elution order is invariably kept if the enantiomers have the same elution order in either one of the two hosts of the binary mixture. In contrast, the elution order may be switched by varying the concentration ratio of two hosts that produce opposite elution order for this particular analyte. In such a dual selector system, the enantioselectivity will disappear at the transient state at a certain ratio of host,:host, Moreover, the migration times of the two enantiomers with host, alone (diluted in buffer) is approximately equal to the migration times at the corresponding concentration of host, alone (diluted in buffer), where the ratio of concentrations of host,:host, is the same as in the binary mixture at the transient state. As found by nuclear magnetic resonance experiments, the analyte is forming a 1:1 complex with either one of the CDs applied. From this finding, a theoretical model based on the mobility difference of the two enantiomers was derived that was used to simulate the transient state. (C) 2000 Elsevier Science B.V. All rights reserved.

EFFECT OF GAMMA-RADIATION ON DYNAMIC VISCOELASTIC PROPERTIES AND THERMAL-BEHAVIOR FOR LDPE

The effect of gamma-radiation on dynamic viscoelastic properties and thermal behavior for low density polyethylene(LDPE) have been investigated. The store energy modulus (E) of the samples increased after radiation. The beta and alpha transition temperature shifted to higher temperature with increasing irradiation dose. The results of thermal analysis show that crystal melting temperature (Tm), enthalpy(DELTAHm) and crystal disapperance temperature(Td) for irradiated samples decreases with increasing of dose.

Chemical Constituents of a Marine-Derived Endophytic Fungus Penicillium commune G2M

Cultivation of the endophytic fungus Penicillium commune, which was isolated from the semi-mangrove plant Hibiscus tiliaceus, afforded one new compound 1-O-(2,4-dihydroxy-6-methylbenzoyl)-glycerol (1) along with thirteen known products, including 1-O-acetylglycerol (2), N-acetyltryptophan (3), 3-indolylacetic acid methyl ester (4), 1-(2,4-dihydroxy-3,5-dimethylphenyl)ethanone (5), 2-(2,5-dihydroxyphenyl)acetic acid (6), (4R,5S)-5-hydroxyhexan-4-olide (7), thymidine (8), uracil (9), thymine (10), ergosterol (11), beta-sitosterol (12), beta-daucosterol (13), and ergosta-7,22-dien-3 beta,5 alpha,6 beta-triol (14). The structures of these compounds were established by detailed NMR spectroscopic analysis, as well as by comparison with literature data or with authentic samples.

Evidence for positive selection in phycoerythrin genes of red algae and cyanobacteria Prochlorococcus and Synechococcus

Because of the shortage of phycoerythrin (PE) gene sequences from rhodophytes, peBA encoding beta- and alpha-subunits of PE from three species of red algae (Ceramium boydenn, Halymenia sinensis, and Plocamium telfariae) were cloned and sequenced. Different selection forces have affected the evolution of PE lineages. 8.9 % of the codons were subject to positive selection within the PE lineages (excluding high-irradiance adapted Prochlorococcus). More than 40 % of the sites may be under positive selection, and nearly 20 % sites are weakly constraint sites in high-irradiance adapted Prochlorococcus. Sites most likely undergoing positive selection were found in the chromophore binding domains, suggesting that these sites have played important roles in environmental adaptation during PE diversification. Moreover, the heterogeneous distribution of positively selected sites along the PE gene was revealed from the comparison of low-irradiance adapted Prochlorococcus and marine Synechococcus, which firmly suggests that evolutionary patterns of PEs in these two lineages are significantly different.

Ergosterimide, a new natural Diels-Alder adduct of a steroid and maleimide in the fungus Aspergillus niger

Ergosterimide (1), a natural Diels-Alder adduct of ergosteroid and maleimide, was characterized from the culture extract of Aspergillus niger EN-13, an endophytic fungus isolated from the marine brown alga Colpomenia sinuosa. In addition, four known steroids including (22E,24R)-ergosta-5,7,22-trien-3 beta-ol (2), (22E,24R)-ergosta-4,6,8(14),22-tetraen-3one (3), (22E,24R)-5 alpha,8 alpha-epidioxyergosta-6,22-dien-3 beta-ol (4), and (22E,24R)-ergosta-7,22dien-3 beta,5 alpha,6 beta-triol. (5) were also isolated and identified. The structures of these compounds were elucidated by extensive analysis of 1D and 2D NMR and IR spectra and MS data. The plausible biosynthetic pathway of 1 was also discussed. To the best of our knowledge, 1 is the first natural Diels-Alder adduct of steroid and maleimide reported so far. (C) 2007 Elsevier Inc. All rights reserved.

Two new diterpenes from Euphorbia kansuensis

Two new lathyrane diterpenes, 3 beta,5 alpha-dihydroxy-15 beta-cinnamonyloxy-14-oxoladiyra-6Z, 12E- diene (1) and 3 beta,5 alpha,20-trihydroxy-15 beta-cinnamoyloxy-14-oxolathyra-6Z, 12E-diene (2), were isolated from the roots of Euphorbia kansuensis. Their structures were determined by spectroscopic methods. (C) 2008 Elsevier B.V. All rights reserved.

A new guaiane diterpenoid from Euphorbia wallichi

A new guaiane-type diterpenoid, (1 alpha, 5 alpha, 7 alpha)-3,10(18), 11-dictytriene-19-acid, was obtained from the roots of Euphorbia wallichii. This is the first isolation of guaiane diterpene from this genus of Euphorbia. The structure was elucidated by spectral methods. And the compound was tested for the cytotoxicities on the cancer cell line P-388 and A-549 in vitro.

ent-kaurene diterpenoids from Isodon rubescens

Two kaurenoids, taibairubescensins A and B, were isolated from the ethanol extract of the leaves and branches of Isodon rubescens. Their structures are designated as 2 beta,3 beta-diacetoxy-11 beta,13 alpha-dihydroxy-ent-kaur-16-en-15-one and 3 beta,11 beta-diacetoxy-2 beta,6 alpha-dihydroxy-ent-kaur-16-en-15-one, respectively, on the basis of detailed spsctroscopic analyses. (C) 2000 Elsevier Science Ltd. All rights reserved.

Two new diterpenoids from Isodon rubescens

Two new diterpenoids taibairubescensin A (1) and B (2) have been isolated from Isodon rubescens. The structures of compound 1 and 2 were elucidated as 2 beta,3 beta-diacetoxy-11 beta,13 alpha-dihydroxy-ent-kaur- 16-en-15-one (1) and 3 beta,11 beta-diacetoxy-2 beta,6 alpha-dihydroxy-ent-kaur-16-en-15-one (2) on the basis of spectroscopic analysis.

释光测年实验室的建立与沉积物释光测年技术研究

The main research projects reported in this paper are the establishment of a luminescence (OSL/TL) dating laboratory in The Institute of Geology and Geophysics, CAS, and studies on OSL dating technique and protocol of sediments from North China. These projects have been suggested in order to fit in with the needs of research developments in environmental changes, in particular the aridity and desertification in North China. A new luminescence dating laboratory in which there are a Rise TL/OSL-DA-15B/C reader with Sr-90 beta source, a set of Little More Tape 9022 alpha and beta irradiators, three set of Daybreak 583 intelligent alpha counters and sample preparation system has been set up in the Institute in June 2001. The courses of the establishment of a new laboratory involved a series of technical works, besides making a suitable choice of the equipment, as follows: installing and testing TL/OSL reader, calibrating the dose rate of the beta and alpha sources in the irradiators with the standard sources, testing and calibrating the count rates of the thick source alpha counting in the alpha counters with a standard sample, and then dating of the know age samples to check and examine the OSL/TL dating system. All data obtained from above calibrations and tests show that the established OSL/TL system, including the used equipment in it, can be used to determine age of the geological and archaeological samples with an error of equivalent dose (De) of less than 5%. The OSL dates of several sediment samples obtained from the system are good agreement with those from the OSL dating laboratory in Hong Kong University and ~(14)C dates within 1 - 2 standard deviations. The studies on OSL dating technique and protocol of sediment samples being in progress involve the De determinations with single aliquot regeneration (SAR) (Murray and Wintle, 2000) of the coarse grain quartz from sand dune samples and comparison of the De determinations obtained from SAR with those measured by using multiple aliquot regeneration of loess fine grains. The preliminary results from these research works are shown as follows. The very low natural equivalent dose (De) of about 0.012 - 0.03 Gy, corresponding age of less than 10 years, for BLSL (blue light stimulated luminescence) of the coarse grain quartz from modern sand dune samples in Horqin sand fields has been determined with both the SAR and multiple aliquot regeneration (MAR) techniques. This imply that the BLSL signal zeroing of the quartz could be reached before burying of the sand in Horqin sand fields. The De values and ages of the coarse grain quartz measured with SAR protocol are in good agreement with those obtained from multiple aliquot technique for the modern sand dune samples, but the errors of De from the MAR is greater than those from the SAR. This may imply that the higher precision of age determination for younger sand dune samples could be achieved with the SAR of coarse grain quartz. The MAR combining with "Australian Slide method" may be a perfect choice for De measurements of loess fine grain samples on the basis of analysis of De values obtained from the SAR and from the MAR. The former can be employed to obtain a reliable age estimate of loess sample as older as approximately SO ka BR There is a great difference between De determinations from the (post-IR) OSL of the SAR (Roberts and Wintle, 2001) and those from independent or expected estimates for the older samples. However, the age estimates obtained from the (post-IR) OSL of the SAR are mostly closed to the independent age determinations for the younger (age less than 10 ka) fine grain samples. It may be suggested that the (post-IR) OSL of the SAR protocol of the fine grain fraction would be a suitable choice to dating of the younger samples, but may be unsuitable for the older samples.

Thermodynamics of the displacive mechanism of alpha(1) transformation in a beta

Thermodynamics of the displacive mechanism of plate-shaped phase alpha(1) was analyzed in beta'Cu-Zn alloys. It was proposed that the displacive transformation of the alpha(1) plate took place in the solute-depleted region formed in the parent phase during the incubation period. The thermodynamic analysis indicated that the driving force of alpha(1) transformation, Delta G, increased with the reduction of x(d), the solute concentration of the depleted region. And, Delta G could overcome-the transformation barrier with solute depletion to a certain degree. In addition, x(d) was higher than the equilibrium concentration in the phase diagram. Therefore, the shear formation of alpha(1) plate in the solute-depleted region was thermodynamically supported.