检索结果-南通市图书馆

Effects of a polyamine inhibitor on the microstructure and macromechanical properties of hydrated shale

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum 2022年第4期8卷 538-545页

作者： Yunlei Hu Xiangchao Shi Qingling Li Leiyu Gao Feng Wu Gang Xie State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500China

China is rich in shale gas resources,however,wellbores in shale gas reservoirs are frequently *** has a serious impact on the shale gas drilling ***,a common additive in water-based shale drilling fluids,can effectively inhibit shale ***,there is a lack of quantitative research on the effect of polyamine inhibitors on the microstructure and macromechanical properties of ***,this study investigated those issues via a systematic hydration experiment carried out on shale from the Longmaxi *** results show that microfractures are created and expand during shale hydration,that they also connect to form a complex microfracture network,and that 3%polyamine inhibitors(polyamine solution with volume fraction of 3%)can effectively inhibit their *** ultrasonic velocities and UCS of the Longmaxi shale are significantly anisotropic;the former first increases and then decreases with the laminae angle,reaching its maximum when the laminae angle is 30°.The UCS of the shale is highest and lowest,respectively,when the laminae angles are 0°or 90°and 30°.In general,these UCS appear as a"U"pattern,high on two sides with a dip in the *** can effectively inhibit both the expansion of shale and the reduction of P-wave and S-wave velocities,the UCS,and elastic *** UCS of a shale sample was reduced by 28%e40%after immersion for 96 h in water,compared to 2%e20%after immersion in a 3%polyamine inhibitor for the same amount of *** inhibiting effect of the polyamine was remarkable.

关键词： polyamine Microfracture Macromechanical properties Hydration Anisotropy

Analysis of a Strong-Inhibition polyamine Drilling Fluid

在线全文

学校读者我要写书评

暂无评论

Fluid Dynamics & Materials Processing 2023年第9期19卷 2431-2447页

作者： Yu Fan Jianhua Guo Xihui Hu Rui Wang Weiqiang Xu Engineering Technology Research Institute Petro China Southwest Oil&Gas Field CompanyChengdu610000China

Drilling technologies based on oil-based drillingﬂuids and strong inhibitory saltwaterﬂuids are affected by draw-backs such as downhole accidents where sticking and wellbore instabilities *** polyamine drillingﬂuids also exhibit problems such as easy decomposition and poor inhibition *** order to mitigate these issues,additives can be used,such as polyamine inhibitors and the synthesis of nanometerﬁltrate *** conducted in the frame of this study with a polyamine drillingﬂuid and such additives show that thisﬂuid has the same inhibitory,plugging,lubricating,and wellbore-stability performances as oil-based drillingﬂ***,it has long-term anti-wear performances even better than those of oil-based drillingﬂ*** out-comes of a series of comparisons with other sample cases(other wells)are reported and the advantages related to the proposedﬂuid discussed in detail.

关键词： High performance polyamine strong inhibition adhesion sticking wellbore stability

Bioinspired Water-soluble Polymers with Grafted polyamine Chains： Synthesis and Complexation with Oligonucleotides

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2018年第10期36卷 1114-1122页

作者： Vadim V.Annenkov Uma Maheswari Krishnan Viktor A.Pal'shin Stanislav N.Zelinskiy Gayathri Kandasamy Elena N.Danilovtseva Limnological Institute of the Siberian Branch of the Russian Academy of Sciences 3 Ulan-Batorskaya St. P.O. Box 278 Irkutsk 664033 Russia Centre for Nanotechnology & Advanced Biomaterials (CeNTAB) School of Chemical and Biotechnology SASTRA University Thanjavur - 613401 Tamil Nadu India

The siliceous frustules of diatom algae contain complex proteins known as silaffins, which consist of a peptide chain with grafted polyamine chains. These polyamines contain twenty or more nitrogen atoms with trimethylene groups between the nitrogens. We synthesized a set of polymers containing grafted long-chain polyamine fragments by using acryloyl chloride （ACh） polymers and activated acrylic acid copolymers as the starting materials. The new polymers contained 0.05 mol%-3.2 mol% of polyamine chains, which corresponded to 0.06-3.56 mmol·g- 1 amine groups. The new amine-containing polymers formed complexes with short （19-21-mer） deoxyribonucleic acid （DNA） and ribonucleic acid （RNA） strands, and these complexes penetrated into model yeast cells and A549 lung cancer cell. This study demonstrates the potential of these species based on long-chain polyamines to serve as novel gene delivery systems.

关键词： polyamine Polymeric amine Gene delivery Acryloyl chloride

Melatonin treatment induces chilling tolerance by regulating the contents of polyamine,γ-aminobutyric acid,and proline in cucumber fruit

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2021年第11期20卷 3060-3074页

作者： Miilion P MADEBO LUO Si-ming WANG Li ZHENG Yong-hua JIN Peng College of Food Science and Technology Nanjing Agricultural UniversityNanjing 210095P.R.China

The mechanism of melatonin(MT)induced chilling tolerance in harvested cucumber fruit was investigated at commercial *** this study,cucumber fruits were treated with 100μmol L^(-1) MT at 4℃ and 90% relative humidity for 15 d of *** comparison with the control,cucumber treatment with MT resulted in reduced chilling injury(CI),decreased electrolyte leakage and enhanced *** fruits treated with MT showed higher chlorophyll contents in storage conditions with suppressed chlorophyllase enzyme *** treatment increased arginine decarboxylase(ADC)and ornithine decarboxylase(ODC)enzyme ***,enhanced expression of the Cucumis sativus ADC(CsADC)and *** ODC(CsODC)genes resulted in the accumulation of polyamine ***,proline levels exhibited higher levels among treated ***,the proline synthesizing enzymes △1-pyrroline-5-carboxylate syntheses(P5CS)and ornithine aminotransferase(OAT)were significantly increased,while a catabolic enzyme of proline dehydrogenase(PDH)activity was inhibited by *** addition,MT induced expression of *** OAT(CsOAT)and *** P5CS(CsP5CS)*** fruits treated with MT also exhibited higher γ-aminobutyric acid(GABA)content by enhanced GABA transaminase(GABA-T)and glutamate decarboxylase(GAD)enzyme activities and a higher *** GAD(CsGAD)gene *** sum up,the results show that MT treatment enhanced chilling tolerance,which was associated with the regulation of polyamines,as well as proline and γ-aminobutyric acid.

关键词： cucumber melatonin polyamine proline GABA chilling injury

Inhibitory effect of agmatine on proliferation of tumor cells by modulation of polyamine metabolism

在线全文

学校读者我要写书评

暂无评论

Acta Pharmacologica Sinica 2005年第5期26卷 616-622页

作者： Ji-fang WANG~2,Rui-bin SU~2,Ning WU,Bo XU,Xin-qiang LU,Yin LIU,Jin LI~3Beijing Institute of Pharmacology and Toxicology,Beijing 100850,China Beijing Institute of Pharmacology and Toxicology Beijing China

Aim:To assess the inhibitory effect of agmatine on tumor growth in vivo andtumor cell proliferation in ***:The transplanted animal model,[~3H]thymidine incorporation assay,3-[4,5-dimethythiazol-2-yl]-2,5-diphenyltetrazo-lium assay,and lactate dehydrogenase(LDH)release assay were ***:Agmatine,at doses of 5-40 mg/kg,suppressed the S180sarcoma tumorgrowth dose-dependently in mice in vivo and the highest inhibitory ratio reached31.3% in Kunming mice and 50.0% in Balb/c mice,*** resultswere obtained in the transplanted B16melanoma tumor ***(1-1000 μmol/L)was able to attenuate the proliferation of cultured MCF-7 humanbreast cancer cells in vitro in a concentration-dependent manner and the highestinhibitory ratio reached 50.3% in the[~3H]thymidine incorporation ***,in the LDH release assay,spermine(20μmol/L)and spermidine(20μmol/L)increased the LDH release significantly,but agmatine(1-1000μmol/L)did not,indicating that the inhibitory effect of agmatine on the proliferation ofMCF was not related to cellular *** the[~3H]thymidine incorporation assay,putrescine(12.5-100.0μmol/L)could reverse the inhibitory effect of agmatine onthe proliferation of MCF concentration-dependently,suggesting that the inhibi-tory effect of agmatine on the proliferation of MCF might be associated with adecreased level of the intracellular polyamines ***:Agmatine hadsignificant inhibitory effect on transplanted tumor growth in vivo and prolifera-tion of tumor cells in vitro,and the mechanism might be a result of inducingdecrease of intracellular polyamine contents.

关键词： agmatine polyamine tumor cell proliferation

Effect of polyamine on seed germination of wheat under drought stress is related to changes in hormones and carbohydrates

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2016年第12期15卷 2759-2774页

作者： LIU Yang XU Hong WEN Xiao-xia LIAO Yun-cheng College of Agronomy Northwest A&F University

Drought is a multifaceted stress condition that inhibits crop growth. Seed germination is one of the critical and sensitive stages of plants, and its process is inhibited or even entirely prevented by drought. polyamines （PAs） are closely associ- ated with plant resistance to drought stress and seed germination. However, little is known about the effect of PA on the seed germination of wheat under drought stress. This study investigated the involvement of PAs in regulating wheat seed germination under drought stress. Six wheat genotypes differing in drought resistance were used, and endogenous PA levels were measured during seed germination under different water treatments. In addition, external PAwas used for seed soaking and the variation of hormones, total soluble sugar and starch were measured during the seed germination under different water treatments. These results indicated that the free spermidine （Spd） accumulation in seeds during the seed germination period favored wheat seed germination under drought stress; however, the free putrescine （Put） accumulation in seeds during the seed germination period may work against wheat seed germination under drought stress. In addition, seed soaking in Spd and spermine （Spm） significantly relieved the inhibition of seed germination by drought stress; howev- er, soaking seeds in Put had no significant effect on seed germination under drought. External Spd and Spm significantly increased the endogenous indole-3-acetic acid （IAA）, zeatin （Z）＋zeatin riboside （ZR）, abscisic acid （ABA）, and gibberellins （GA） contents in seeds and accelerated the seed starch degradation and increased the concentration of soluble sugars in seeds during seed germination. This may promote wheat seed germination under drought stress. In conclusion, free Spd and Put are key factors for regulating wheat seed germination under drought stress and the effects of Spd and Put on seed germination under drought notably related to hormones and starch metab

关键词： polyamine drought seed germination wheat abscisic acid starch

Improvement of plant abiotic stress tolerance through modulation of the polyamine pathway

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2014年第2期56卷 114-121页

作者： Haitao Shi Zhulong Chan Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture Wuhan Botanical Gardenthe Chinese Academy of Sciences

polyamines （mainly putrescine （Put）, spermidine （Spd）, and spermine （Spin）） have been widely found in a range of physiological processes and in almost all diverse environ- mental stresses. In various plant species, abiotic stresses modulated the accumulation of polyamines and related gene expression. Studies using loss-of-function mutants and transgenic overexpression plants modulating polyamine metabolic pathways confirmed protective roles of polyamines during plant abiotic stress responses, and indicated the possibility to improve plant tolerance through genetic manipulation of the polyamine pathway. Additionally, puta- tive mechanisms of polyamines involved in plant abiotic stress tolerance were thoroughly discussed and crosstalks among polyamine, abscisic acid, and nitric oxide in plant responses to abiotic stress were emphasized. Special attention was paid to the interaction between polyamine and reactive oxygen species, ion channels, amino acid and carbon metabolism, and other adaptive responses. Further studies are needed to elucidate the polyamine signaling pathway, especially polyamine-regulated downstream tar- gets and the connections between polyamines and other stress responsive molecules.

关键词： Abiotic stress crosstalk polyamine polyamine metabolic pathway transgenic plants

Design, synthesis and evaluation of genistein-polyamine conjugates as multi-functional anti-Alzheimer agents

在线全文

学校读者我要写书评

暂无评论

Acta Pharmaceutica Sinica B 2015年第1期5卷 67-73页

作者： Xin Zhang Jiang Wang Chen Hong Wen Luo Chaojie Wang Key Laboratory of Natural Medicine and Immuno-Engineering Henan University

A series of genistein-polyamine conjugates(4a–4h) were designed, synthesized and evaluated as multi-functional anti-Alzheimer agents. The results showed that these compounds had significant cholinesterases(Ch Es) inhibitory activity. Compound 4b exhibited the strongest inhibition to acetylcholinesterase(ACh E) with an IC_(50) value of 2.75 μmol/L, which was better than that of rivastigmine(5.60 μmol/L). Lineweaver–Burk plot and molecular modeling study showed that compound 4b targeted both the catalytic active site(CAS) and the peripheral anionic site(PAS) of ACh E. Besides, compound 4b showed potent metal-chelating ability. In addition, it was found that 4a–4h did not affect Hep G-2 cell viability at the concentration of 10 μmol/L.

关键词： Genistein polyamine Alzheimer’s disease Acetylcholinesterase Molecular modeling Metal-chelating Inhibition Rivastigmine

RELATION OF polyamine TITER TO THYMUS DEGENERATION IN MICE

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1989年第8期34卷 677-682页

作者：戴尧仁赵米金柴真 Department of Biology Peking University

There is a growing body of evidence in recent years that aging is closely related to the decline in the function of immune system, particularly the cellular immune system of various organisms. Because of the extraordinary role played by the thymus as a central lymph organ, the investigation on the interrelation between thymus degeneration and aging has naturally received particular attention.

关键词： polyamine putrescine thymus degeneration dexamethasone.