Showing papers by "Nanchang University published in 2006"

Impacts of genetic bottlenecks on soybean genome diversity.

Abstract: Soybean has undergone several genetic bottlenecks These include domestication in Asia to produce numerous Asian landraces, introduction of relatively few landraces to North America, and then selective breeding over the past 75 years It is presumed that these three human-mediated events have reduced genetic diversity We sequenced 111 fragments from 102 genes in four soybean populations representing the populations before and after genetic bottlenecks We show that soybean has lost many rare sequence variants and has undergone numerous allele frequency changes throughout its history Although soybean genetic diversity has been eroded by human selection after domestication, it is notable that modern cultivars have retained 72% of the sequence diversity present in the Asian landraces but lost 79% of rare alleles (frequency ≤010) found in the Asian landraces Simulations indicated that the diversity lost through the genetic bottlenecks of introduction and plant breeding was mostly due to the small number of Asian introductions and not the artificial selection subsequently imposed by selective breeding The bottleneck with the most impact was domestication; when the low sequence diversity present in the wild species was halved, 81% of the rare alleles were lost, and 60% of the genes exhibited evidence of significant allele frequency changes

Black-hole thermodynamics with modified dispersion relations and generalized uncertainty principles

Abstract: In several approaches to the quantum-gravity problem evidence has emerged of the validity of a 'GUP' (a generalized position–momentum uncertainty principle) and/or a 'MDR' (a modification of the energy–momentum dispersion relation), but very little is known about the implications of GUPs and MDRs for black-hole thermodynamics, another key topic for quantum-gravity research. We investigate an apparent link, already suggested in an earlier exploratory study involving two of us, between the possibility of a GUP and/or an MDR and the possibility of a log term in the area–entropy black-hole formula. We then obtain, from that same perspective, a modified relation between the mass of a black hole and its temperature, and we examine the validity of the 'generalized second law of black-hole thermodynamics' in theories with a GUP and/or an MDR. After an analysis of GUP- and MDR-modifications of the black-body radiation spectrum, we conclude the study with a description of the black-hole evaporation process.

Interacting dark energy, holographic principle, and coincidence problem

Abstract: The interacting and holographic dark energy models involve two important quantities. One is the characteristic size of the holographic bound and the other is the coupling term of the interaction between dark energy and dark matter. Rather than fixing either of them, we present a detailed study of theoretical relationships among these quantities and cosmological parameters as well as observational constraints in a general formalism. In particular, we argue that the ratio of dark matter to dark energy density depends on the choice of these two quantities, thus providing a mechanism to change the evolution history of the ratio from that in standard cosmology such that the coincidence problem may be solved. We investigate this problem in detail and construct explicit models to demonstrate that it may be alleviated provided that the interacting term and the characteristic size of holographic bound are appropriately specified. Furthermore, these models are well fitted with the current observation at least in the low redshift region.

Atom transfer radical polymerization directly from poly(vinylidene fluoride): Surface and antifouling properties

Abstract: The direct preparation of grafting polymer brushes from commercial poly (vinylidene fluoride) (PVDF) films with surface-initiated atom transfer radical polymerization (ATRP) is demonstrated. The direct initiation of the secondary fluorinated site of PVDF facilitated grafting of the hydrophilic monomers from the PVDF surface. Homopolymer brushes of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) and poly (ethylene glycol) monomethacrylate (PEGMA) were prepared by ATRP from the PVDF surface. The chemical composition and surface topography of the graft-functionalized PVDF surfaces were characterized by X-ray photoelectron spectroscopy, attenuated total reflectance/Fourier transform infrared spectroscopy, and atomic force microscopy. A kinetic study revealed a linear increase in the graft concentration of poly[2-(N,N-dimethylamino)ethyl methacrylate] (PDMAEMA) and poly[poly(ethylene glycol) monomethacrylate] (PPEGMA) with the reaction time, indicating that the chain growth from the surface was consistent with a controlled or living process. The living chain ends were used as macroinitiators for the synthesis of diblock copolymer brushes. The water contact angles on PVDF films were reduced by the surface grafting of DMAEMA and PEGMA. Protein adsorption experiments revealed a substantial antifouling property of PPEGMA-grafted PVDF films and PDMAEMA-grafted PVDF films in comparison with the pristine PVDF surface.

Lyapunov indices with two nearby trajectories in a curved spacetime

Abstract: We compare three methods for computing invariant Lyapunov exponents (LEs) in general relativity. These methods involve the geodesic deviation vector technique (M1), the two-nearby-orbits method with projection operations and with coordinate time as the independant variable (M2), and the two-nearby-orbits method without projection operations and with proper time as the independent variable (M3). An analysis indicates that M1 and M3 do not need any projection operation. In general, the values of LEs from the three methods are almost the same. However, M2 fails for some specific cases. As a result, M3 is the most preferable to calculate LEs in most cases. In addition, we propose to construct the invariant fast Lyapunov indictor (FLI) with two-nearby-trajectories and give its algorithm in order to quickly distinguish chaos from order. Taking a static axisymmetric spacetime as a physical model, we apply different algorithms of the FLI to explore the global dynamics of phase space of the system where regions of chaos and order are clearly identified.

Simultaneous determination of five synthetic antioxidants in edible vegetable oil by GC–MS

Abstract: A simple, quick and nontoxic analytical method for the simultaneous determination of five synthetic antioxidants [t-butyl-4-hydroxyanisole (BHA), 2,6-di-t-butyl-hydroxytoluene (BHT), t-butyl hydroquinone (TBHQ), ethoxyquin (EQ) and 2,6-di-tert-butyl-4-hydroxymethyl-phenol (Ionox 100)] in edible vegetable oil has been developed. The analytes were extracted by ethanol, then separated and detected by GC–MS. Extraction conditions such as volume of ethanol required, mixing time and number of extractions were investigated and optimized by an orthogonal array experimental design. The five compounds behaved linearly in the 0.100∼20.0 mg/L concentration range, and the limits of detection (LOD) for BHA, BHT, TBHQ, EQ and Ionox-100 were 1.00, 0.92, 11.5, 0.83 and 1.39 μg/L, respectively. The recoveries at the tested concentrations of 1.00, 20.0 and 100 mg/kg were 75.6∼123%, with coefficients of variation <10.0%. The proposed procedure was successfully applied to the simultaneous analysis of the five antioxidants in soybean oil, tea oil, edible blended oil, rap oil, peanut oil, peanut blended oil and sesame oil samples purchased from local supermarkets.

A novel color image segmentation method and its application to white blood cell image analysis

Abstract: According to the fact that the H component in HSI color space contains most of the white blood cell information, and the S component contains the structure information of the white blood cell nucleus, we develop an iterative Otsu's approach based on circular histogram for the leukocyte segmentation by taking full advantage of this knowledge. Experimental results show that this method works successfully in the segmentation of color smear microscopic images

A unique NH-spacer for N-benzamidothiourea based anion sensors. Substituent effect on anion sensing of the ICT dual fluorescent N-(p-dimethylaminobenzamido)-N′-arylthioureas

Abstract: A series of N-(p-dimethylaminobenzamido)-N′-(substituted-phenyl)thioureas (substituent = p-CH3, H, p-Cl, p-Br, m-Br, m-NO2, and p-NO2) were designed as anion sensors in order to better understand the –NH-spacer via a substituent effect investigation. In these molecules the dual fluorescent intramolecular charge transfer (ICT) fluorophore p-dimethylaminobenzamide as the signal reporter was linked to the anion-binding site, the thiourea moiety, via an N–N single bond. Correlation of the NMR signals of the aromatic and –NH protons with substituents in these molecules indicated that the N–N single bond stopped the ground-state electronic communication between the signal reporter and the anion-binding site. Dual fluorescence was observed in highly polar solvents such as acetonitrile with the former five derivatives. The fact that the CT emission wavelength and the CT to LE emission intensity ratio of the sensors were independent of the substituent existing in the anion-binding moiety suggested that the substituent electronic effect could not be communicated to the CT fluorophore in the excited-state either. Yet in acetonitrile both the CT dual fluorescence and the absorption of the sensors were found to be highly sensitive toward anions. A conformation change around the N–N bond in the sensor molecules was suggested to occur upon anion binding that established the electronic communication between the signal reporter and the anion-binding site. The anion binding constants of the N-(p-dimethylaminobenzamido)thiourea sensors were found higher than those of the corresponding traditional N-phenylthiourea counterparts and the substituent effect on the anion binding constant was much higher than that in the latter. “–NH–“ was shown to be a unique spacer that affords N-benzamidothiourea allosteric anion sensors.

Modified dispersion relations and black hole physics

Abstract: A modified formulation of the energy-momentum relation is proposed in the context of doubly special relativity. We investigate its impact on black hole physics. It turns out that such a modification will give corrections to both the temperature and the entropy of black holes. In particular, this modified dispersion relation also changes the picture of Hawking radiation greatly when the size of black holes approaches the Planck scale. It can prevent black holes from total evaporation, as a result providing a plausible mechanism to treat the remnant of black holes as a candidate for dark matter.

Liquefaction of corn stover and preparation of polyester from the liquefied polyol.

Abstract: This research investigated a novel process to prepare polyester from corn stover through liquefaction and crosslinking processes. First, corn stover was liquefied in organic solvents (90 wt% ethylene glycol and 10 wt% ethylene carbonate) with catalysts at moderate temperature under atmospheric pressure. The effect of liquefaction temperature, biomass content, and type of catalyst, such as H2SO4, HCl, H3PO4, and ZnCl2, was evaluated. Higher liquefaction yield was achieved in 2 wt% sulfuric acid, 1/4 (w/w) stover to liquefying reagent ratio; 160°C temperature, in 2 h. The liquefied corn stover was rich in polyols, which can be directly used as feedstock for making polymers without further separation or purification. Second, polyester was made from the liquefied corn stover by crosslinking with multifunctional carboxylic acids and/or cyclic acid anhydrides. The tensile strength of polyester is about 5 MPa and the elongation is around 35%. The polyester is stable in cold water and organic solvents and readily biodegradable as indicated by 82% weight loss when buried in damp soil for 10 mo. The results indicate that this novel polyester could be used for the biodegradable garden mulch film production.

Controlled grafting from poly(vinylidene fluoride) films by surface‐initiated reversible addition–fragmentation chain transfer polymerization

Abstract: A reversible addition–fragmentation chain transfer (RAFT) polymerization technique was applied to graft polymerize brushes of poly(methyl methacrylate) (PMMA) and poly(poly(ethylene glycol) monomethacrylate) (PPEGMA) from poly(vinylidene fluoride) (PVDF) surfaces. PVDF surfaces were exposed to aqueous LiOH, followed by successive reductions with NaBH4 and DIBAL-H to obtain hydroxyl functionality. Azo-functionalities, as surface initiators for grafting, were immobilized on the PVDF surfaces by esterification of 4,4′-azobis(4-cyanopentanoic acid) and the surface hydroxyl groups. The chemical composition and surface topography of the graft-functionalized PVDF surfaces were characterized by X-ray photoelectron spectroscopy, attenuated total reflectance-FTIR spectroscopy, and atomic force microscopy. Kinetics studies revealed a linear increase in the graft concentration of PMMA and PPEGMA with the reaction time, indicating that the chain growth from the surface was consistent with a “controlled” or “living” process. The living chain ends were used as the macroinitiator for the synthesis of diblock copolymer brushes. Water contact angles on PVDF films were reduced by surface grafting of PEGMA and MMA. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3071–3082, 2006

Determination of speciation of elements related to blood sugar in bioactive extracts from Cyclocarya paliurus leaves by FIA-ICP-MS

Abstract: This paper describes the development and application of FIA-ICP-MS technique for the speciation of trace elements in extracts of Cyclocarya Paliurus (Batal.) Iljinsk (CP) leaves, an herbal tea used widely in China as dietary supplement for Elements Related to Blood Sugar (ERBS), which are reported to have the beneficial effects of lowering blood sugar. Most ERBSs are found to be water-soluble. On the basis of elemental distribution, the aqueous solutions of CP of different origins can be separated into two groups: one is rich in organo-magnesium, organo-manganese, organo-zinc, inorganic copper, and inorganic nickel; while the other is rich in inorganic magnesium, inorganic manganese, inorganic copper, inorganic nickel and organo-zinc. The ERBSs in two bioactive extracts of CP named EE and POLY were analyzed and compared, and the results suggest that the extracts are good dietary supplement for people, especially Diabetes Mellitus (DM) patients through the provision of ERBSs of Mn, Zn, Mg, Cu, and Ni in organic or inorganic forms.

Genome-wide analyses of retrogenes derived from the human box H/ACA snoRNAs

Abstract: The family of box H/ACA snoRNA is an abundant class of non-protein-coding RNAs, which play important roles in the post-transcriptional modification of rRNAs and snRNAs. Here we report the characterization in the human genome of 202 sequences derived from box H/ACA snoRNAs. Most of them were retrogenes formed using the L1 integration machinery. About 96% of the box H/ACA RNA-related sequences are found in corresponding locations on the chimpanzee and human chromosomes, while the mouse shares approximately 50% of these human sequences, suggesting that some of the H/ACA RNA-related sequences in primate occurred after the rodent/primate divergence. Of the H/ACA RNA-related sequences, 49% are found in intronic regions of protein-coding genes and 64 H/ACA-related sequences can be folded to the typical secondary structure of the box H/ACA snoRNA family, while 30 of them were recognized as functional homologs of their corresponding box H/ACA snoRNAs previously reported. Of the 64 sequences with the typical secondary structure of the box H/ACA RNA family, 11 were found in EST databases and 5 among which were shown to be expressed in more than one human tissue. Notably, U107f is nested in an intron of a protein gene coding for nudix-type motif 13, but expressed from the opposite strand, and the searching of EST databases revealed it can be expressed in liver and spleen, even in melanotic melanoma.

Strong Vector Equilibrium Problems

Abstract: In this paper, the existence of the solution for strong vector equilibrium problems is studied by using the separation theorem for convex sets. The arc-wise connectedness and the closedness of the strong solution set for vector equilibrium problems are discussed; and a necessary and sufficient condition for the strong solution is obtained.

Controlled grafting of polymer brushes on poly(vinylidene fluoride) films by surface-initiated atom transfer radical polymerization

Abstract: Controlled grafting of well-defined polymer brushes on the poly(vinylidene fluoride) (PVDF) films was carried out by the surface-initiated atom transfer radical polymerization (ATRP). Surface-initiators were immobilized on the PVDF films by surface hydroxylation and esterification of the hydroxyl groups covalently linked to the surface with 2-bromoisobutyrate bromide. Homopolymer brushes of methyl methacrylate (MMA) and poly(ethylene glycol) monomethacrylate (PEGMA) were prepared by ATRP from the α-bromoester-functionalized PVDF surface. The chemical composition of the graft-functionalized PVDF surfaces was characterized by X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance (ATR)–FTIR spectroscopy. Kinetics study revealed a linear increase in the graft concentration of PMMA and PEGMA with the reaction time, indicating that the chain growth from the surface was consistent with a “controlled” or “living” process. The “living” chain ends were used as the macroinitiator for the synthesis of diblock copolymer brushes. Water contact angles on PVDF films were reduced by surface grafting of PEGMA and MMA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3704–3712, 2006

Molecular mechanism of osteochondroprogenitor fate determination during bone formation

Abstract: Osteoblasts and chondrocytes, which derive from a common mesenchymal precursor (osteochondroprogenitor), are involved in bone formation and remodeling in vivo. Determination of osteochondroprogenitor fate is under the control of complex hormonal and local factors converging onto a series of temporospatial dependent transcription regulators. Sox9, together with L-Sox5 and Sox6, of the Sox family is required for chondrogenic differentiation commitment, while Runx2/Cbfa1, a member of runt family and Osterix/Osx, a novel zinc finger-containing transcription factor play a pivotal role in osteoblast differentiation decision and hypertrophic chondrocyte maturation. Recent in vitro and in vivo evidence suggests β-catenin, a transcriptional activator in the canonical Wnt pathway, can act as a determinant factor for controlling chondrocyte and osteoblast differentiation. Here we focus on several intensively studied transcription factors and Wnt/β-catenin signal molecules to illustrate the regulatory mechanism in directing commitment between osteoblast and chondrocyte, which will eventually allow us to properly manipulate the mesenchymal progenitor cell differentiation on bone and regeneration of cartilage tissue engineering.

Chaotic Dynamics in a Superposed Weyl Spacetime

Abstract: A general superposed solution between a Schwarzschild black hole and one of the first family of Lemos-Letelier disks with two opposite dipoles is given. For the Newtonian core-disk system, it is integrable in the region z > 0 or <0, but it might be nonintegrable over the global interval of z since the Newtonian potential from the disk has discontinuous derivatives. On the other hand, Poincare sections reveal that the dynamics of test particles in the relativistic core-disk system depends on some specified dynamical parameters. The system goes from regular to chaotic with increasing disk parameter. In addition, other parameters such as energy and angular momentum have an impact on chaos. The larger the energy gets, or the smaller the angular momentum becomes, the more dramatic chaos the system produces. If the interaction term between the black hole and the disk is dropped, chaos seems to die out. This fact illustrates sufficiently that the nonlinearity of the Einstein field equations is a crucial factor for the onset of chaos. Note, as a crucial point, that there is a much thinner chaotic domain trapped in a larger regular region in the case of larger angular momenta, unlike the case of smaller angular momenta. This can also be described by the spectral analysis and the invariant Lyapunov exponents.