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SYNTHESIS OF AN EPOXY-TERMINATED HYPERBRANCHED AROMATIC POLYESTER

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Chinese Journal of Polymer Science 2002年第6期20卷 585-590页

作者： W.J.Feast IRC in Polymer Science and Technology Durham University South Road Durham DH1 3LE UK

An epoxy-terminated hyperbranched aromatic polyester (P3) was synthesized from a hyperbranched aromatic polyester containing carboxylic acid end groups (P1), which was derived from the condensation polymerization of the AB(2) monomer, 5-acetoxyisophthalic acid. Polymer P1 was converted into the polymeric acid chloride by reaction with thionyl chloride. The acid chloride was reacted with ethanol and glycidol to form a poly(ethyl ester) (P2) and an epoxy terminated material (P3), respectively. The reaction conditions in each step of these processes had to be controlled very carefully to avoid unwanted cross-linking reactions. The characterization of products and intermediates, including molecular weight distributions and thermal properties, are reported.

关键词： hyperbranched polymer hyperbranched aromatic polyester epoxy-terminated hyperbranched aromatic polyester

M-Theory in the Gaugeon Formalism

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Communications in Theoretical Physics 2012年第4期57卷 637-640页

作者： Mir Faizal Department of Mathematics Durham UniversityDurhamDH1 3LEUnited Kingdom

In this paper we will analyse the Aharony-Bergman-Jafferis-Maldacena(ABJM) theory in N = 1 superspace *** then study the quantum gauge transformations for this ABJM theory in gaugeon *** will also analyse the extended BRST symmetry for this ABJM theory in gaugeon formalism and show that these BRST transformations for this theory are nilpotent and this in turn leads to the unitary evolution of the S-matrix.

关键词： ABJM gaugeon BRST N = 1 superspace

Corrosion Behaviours of Copper Alloy in Solutions Containing Na_2SO_4 and NaCl with Different Concentrations

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Journal of Materials Science & Technology 2002年第6期18卷 549-551页

作者： A.A.El-Meligi Chem. Dept. Durham Univ. Durham DH1 3LE South Road United Kingdom

Potentiodynamic polarisation, potential-time measurements, X-ray diffraction (XRD) and infrared spectroscopy (IR) have been used to investigate the effect of different concentrations of Na2SO4 in the absence and presence of NaCI, on the corrosion of Cu-alloy. The electrochemical measurements showed that the increase of Na2SO4 concentration led to increase the corrosion current density of Cu alloy and vice versa. The presence of NaCI shifted the potential to more cathodic potential, which had a great influence on the protectiveness of the Cu oxide layer formed on the surface in presence of Na2SO4. The spectrometric measurements indicated the constituents of the film formed on the alloy surface were mainly Cu2O, in addition to the oxides, NiO and Fe2O3, which were traced by XRD analysis.

关键词： Cu-alloy Polarisation X-ray diffraction Na2SO4 NaCl Oxide film

On the great plume debate

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Chinese Science Bulletin 2005年第15期50卷 1537-1540页

作者： Yaoling Niu Department of Earth Sciences Durham University Durham DH1 3LE UK

1 Introductory noteGeological processes are ultimately consequences of Earth's thermal evolution. Plate tectonic theory, which explains geological phenomena along plate boundaries, elegantly illustrates this concept. For example, the origin of oceanic plates at ocean ridges, the movement and growth of these plates, and their ultimate consumption back into the Earth's deep interior through subduction zones provide an efficient mechanism to cool the earth's mantle, leading to large-scale mantle convection. Mantle plumes, which explain another set of global geological phenomena such as within-plate volcanism, cool the earth's deep interior (probably the Earth's core) and represent another mode of Earth's thermal convection. Plate tectonic theory and mantle plume hypothesis thus complement each other to explain much of the whole picture of Earth processes and phenomena.

关键词：地质学地球科学热量边界性质海洋特性

Reservoir quality of fluvial sandstone reservoirs in salt-walled mini- basins： an example from the Seagull field, Central Graben, North Sea, UK

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Petroleum Science 2018年第1期15卷 1-27页

作者： Stephan Stricker Stuart J.Jones Neil Meadows leon Bowen Department of Earth Sciences Durham University South Road Durham DH1 3LE UK RedRock Associates International Limited 38 Queens DrivePrenton Wirral CH43 0RP UK Department of Physics Durham University South RoadDurham DH1 3LE UK

The Triassic fluvial sandstones of the Skagerrak Formation were deposited in a series of salt-walled mini-basins and act as important hydrocarbon reservoirs for several high-pressure, high-temperature（HPHT） fields in the Central Graben, North Sea. The HPHT reservoirs exhibit excellent reservoir quality considering their depth of burial and hence have been of high interest for hydrocarbon exploration. This research uses a multidisciplinary approach to assess the Skagerrak Formation fluvial reservoir quality from the Seagull field incorporating core analysis, petrography, electron microscopy, XRD analysis, fluid inclusion appraisal and burial history modelling. Halokinesis and salt withdrawal at the margin of the saltwalled mini-basin induced early disaggregation bands and fractures at shallow burial and led to increased influx of meteoric water and clay mineral infiltration from overlying sedimentation. The density of disaggregation bands correlates with the occurrence and magnitude of pore-filling authigenic clay minerals, concentrated along the margin of the saltwalled mini-basin. The fluvial channel sandstones of the Skagerrak Formation are subject to strong intra-basinal spatial reservoir quality variations despite diagenesis and low vertical effective stress having played a favourable role in arresting porosity loss.

关键词： Reservoir quality Halokinesis - Diagenesis Clay minerals Porosity Disaggregation bands Salt-walled mini-basin

Constitutive modeling of viscoelastic-viscoplastic behavior of short fiber reinforced polymers coupled with anisotropic damage and moisture effects

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Acta Mechanica Sinica 2019年第3期35卷 495-506页

作者： Ge He Yucheng Liu Xingqiao Deng lei Fan Department of Mechanical Engineering Mississippi State UniversityStarkville 39762USA School of Mechanical Engineering and Automation Xihua UniversityChengdu 610039China Department of Engineering Durham UniversityDurham DH1 3LEUK

In this paper, a combined viscoelasticity-viscoplasticity model, coupled with anisotropic damage and moisture effects, is developed for short fiber reinforced polymers (SFRPs) with different fiber contents and subjected to a variety of strain rates. In our model, a rate-dependent yield surface for the matrix phase is employed to identify initial yielding of the material. When an SFRP is loaded at small deformation before yielding, its viscoelastic behavior can be described using the generalized Maxwell model, while when plasticity occurs, a scalar internal state variable (ISV) is used to capture the hardening behavior caused by the polymeric constituent of the composite. The material degradation due to the moisture absorption of the composite is modeled by employing another type of ISV with different evolution equations. The complicated damage state of the SFRPs is captured by a second rank tensor, which is further decomposed to model the subscale damage mechanisms of micro-voids/cracks nucleation, growth and coalescence. It is concluded that the proposed constitutive model can be used to accurately describe complicated behaviors of SFRPs because the results predicted from the model are in good agreement with the experimental data.

关键词： Short fiber reinforced polymer Internal state variable Anisotropic damage Moisture effect Viscoelasticity-viscoplasticity

Mantle plumes: Why the current skepticism?

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Chinese Science Bulletin 2005年第15期50卷 1555-1560页

作者： Gillian R. Foulger Department of Earth Sciences Science Laboratories University of Dur-ham South Rd. Durham DH1 3LE U.K.

The present reappraisal of the mantle plume hypothesis is perhaps the most exciting current debate in Earth science. Nevertheless, the fundamental reasons for why it has arisen are often not well understood. They are that 1) many observations do not agree with the predictions of the original model, 2) it is possible that convection of the sort required to generate thermal plumes in the Earth’s mantle does not occur, 3) so many variants of the original model have been invoked to accommodate conflicting data that the plume hypthesis is in practice no longer testable, and 4) al-ternative models are viable, though these have been largely neglected by researchers. Regardless of the final outcome, the present vigorous debate is to be welcomed since it is likely to stimulate new discoveries in a way that unquestioning acceptance of the conventional plume model will not.

关键词：地质学火山热量对流移动覆盖物地球科学

A Novel RGL2-DOF6 Complex Contributes to Primary Seed Dormancy in Arabidopsis thaliana by Regulating a GATA Transcription Factor

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Molecular Plant 2017年第10期10卷 1307-1320页

作者： Pratibha Ravindran Vivek Verma Petra Stamm Prakash P. Kumar Department of Biological Sciences Faculty of Science National University of Singapore Singapore 117543 Singapore present address: Department of Biosciences Durham University South Road Durham DH1 3LE UK

The DELLA protein RGA-LIKE2 （RGL2） is a key transcriptional repressor of gibberellic acid （GA） signaling that regulates seed germination. We identified GATA12, a gene encoding a GATA-type zinc finger transcription factor, as one of the downstream targets of RGL2 in Arabidopsis thaliana. Our data show that freshly harvested （unstratified） seeds of GATA 12 antisense suppression lines have reduced dormancy compared with the wild-type, while ectopic expression lines show enhanced seed dormancy. We show that GATA12 expression is negatively regulated by GA, and its transcript levels decline dramatically under dormancy- breaking conditions such as dry storage and cold stratification of seeds. GATA12 promoter has several GAMYB- and DOF-associated motifs that are known to be GA- and RGL2-responsive, respectively. Chromatin immunoprecipitation assay showed that a protein complex containing RGL2 can bind to GATA12 promoter and thereby regulate its expression. RGL2 lacks a DNA binding domain and requires a transcription factor to induce GATA12 expression. Our data show that this RGL2-containing protein complex includes DNA BINDING1 ZINC FINGER6 （DOF6）, which is a known negative regulator of germination in freshly harvested seeds. We further show that this novel RGL2-DOF6 complex is required for activating GATA12 expression, thus revealing a molecular mechanism to enforce primary seed dormancy.

关键词： seed germination primary dormancy DELLA RGL2 DOF6 gibberellin

An evaluation of garlic lectin as an alternative carrier domain for insecticidal fusion proteins

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Insect Science 2008年第6期15卷 483-495页

作者： Elaine Fitches Judith Philip Gareth Hinchliffe leisbeth Vercruysse Nanasaheb Chougule John A. Gatehouse Central Science Laboratory Sand Hutton York Y041 1LZ UK School of Biological and Biomedical Sciences Durham University South Road Durham DH1 3LE UK

The mannose-binding lectin GNA （snowdrop lectin） is used as a＂carrier＂ domain in insecticidal fusion proteins which cross the insect gut after oral ingestion. A similar lectin from garlic bulb, ASAII, has been evaluated as an alternative ＂carrier＂. Recombinant ASAII delivered orally to larvae of cabbage moth （Mamestra brassica; lepidoptera） was subsequently detected in haemolymph, demonstrating transport. Fusion proteins comprising an insect neurotoxin, ButaIT （Buthus tamulus insecticidal toxin; red scorpion toxin） linked to the C-terminal region of ASAII or GNA were produced as recombinant proteins （GNA/ ButaIT and ASA/ButaIT） by expression in Pichia pastoris. In both cases the C-terminal sequence of the lectin was truncated to avoid post-translational proteolysis. The GNA- containing fusion protein was toxic by injection to cabbage moth larvae （LD50≈ 250μg/g）, and when fed had a negative effect on survival and growth. It also decreased the survival of cereal aphids （Sitobion avenae; Homoptera） from neonate to adult by 〉70% when fed. In contrast, the ASA-ButaIT fusion protein was non-toxic to aphids, and had no effect on lepidopteran larvae, either when injected or when fed. However, intact ASA-ButaIT fusion protein was present in the haemolymph of cabbage moth larvae following ingestion, showing that transport of the fusion had occurred. The stabilities of GNA/ButaIT and ASA/ButaIT to proteolysis in vivo after injection or ingestion differed, and this may be a factor in determining insecticidal activities.

关键词： Allium sativum lectin ASAII gut to haemolymph transport Pichia pastoris expression system stability to proteolysis