25 research outputs found
Bioinformatic Analysis of Disease-Associated Alternative Splicing genes and Codon-Complementary Codons
遗传密码子(GeneticCodes)是连接基因和蛋白质的桥梁。通过研究密码子与互补密码子在疾病选择性剪接形成及物种进化中使用频率的差异,将有助于从新的角度来了解选择性剪接的进化及其导致人类疾病的可能分子机制。本文统计分析了118个人类疾病相关的选择性剪接基因编码区中2,903个单核苷酸替代的特征:在选择性剪接基因的单碱基替代中,最普通的替代类型依次是C|T(C/T或T/C)(31.97%)和A|G(28.14%)替换、G|T(13.65%)和C|G(12.47%),A|C和A|T替换是较少的,分别为7.44%和6.34%。转换(A|G和C|T)60.11%大于颠换(A|C、G|T、A|T和C...Genetic code is the biological language in communication between DNA andprotein. To reveal the role of different usage of genetic codons and theircomplementary codons in the evolution of disease-associated alternative splicing,118 alternatively spliced human genes with 2,903 nucleotide substitutions werestatistically analyzed. It is found that nucleotide tranitions has overallpreponderance over nu...学位:理学硕士院系专业:生命科学学院生物学系_生物化学与分子生物学学号:20032609
Preparation and Characterization of Sinter-Resistant RhSm2O3/SiO2 Catalyst and Its Performance for Partial Oxidation of Methane to Syngas
以乙酰丙酮铑(Rh(acac)_3)和乙酰丙酮钐(Sm(acac)_3)为前驱体,用浸渍法制备了Rh/SiO_2和Rh-Sm_2O_3/SiO_; 2催化剂。采用原位红外光谱、热重分析、低温N_2吸附、X射线粉末衍射、高分辨透射电子显微镜、H_2-程序升温还原和X射线光电子能谱等实验技术对催; 化剂的制备过程,比表面积和物相以及Rh与Sm_2O_3间的相互作用进行了表征,并以甲烷部分氧化制合成气为目标反应对催化剂的稳定性进行了考察。研究; 表明:以Rh(acac)_3和Sm(acac)_3为前驱体采用简单的浸渍法即可制备出Rh平均粒径为2.3; nm且具有良好抗烧结性能的Rh-Sm_2O_3/SiO_2催化剂。在浸渍过程中乙酰丙酮化合物通过与SiO_2表面羟基形成氢键而负载于载体表面。S; m(acac)_3在SiO_2表面的单层负载量(质量分数)约为31%,对应于Sm_2O_3的质量分数约为15%,只要Sm(acac)_3的质量分; 数低于这一阈值,均可保证分解后生成的Sm_2O_3以高分散形式负载于SiO_2上,且不会因高温(800; °C)焙烧而团聚。高分散于SiO_2表面的Sm_2O_3与Rh之间存在强的相互作用,可显著提高Rh的分散度,防止其在高温反应条件下烧结,进而使低; Rh负载量的催化剂表现出良好的甲烷部分氧化制合成气反应活性和稳定性。Rh/SiO2 and Rh-Sm2O3/SiO2 catalysts were synthesized by the conventional impregnation method using rhodium acetylacetonate (Rh(acac)(3)) and samarium acetylacetonate (Sm(acac)(3)) as precursors. The preparation and catalytic properties, as well as the interaction between Rh and Sm2O3, were characterized in detail by in situ infrared spectroscopy (IR), thermogravimetric analysis (TG), N-2 physisorption (Brunauer-Emmett-Teller (BET) method), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), temperature-programmed reduction (H-2-TPR) and X-ray photoelectron spectroscopy (XPS). The performance of the catalysts for the partial oxidation of methane (POM) to syngas was also investigated. The results showed that a sinter-resistant Rh-Sm2O3/SiO2 catalyst with an average Rh particle size of similar to 2.3 nm could be synthesized using the conventional impregnation method with Rh(acac)(3) and Sm(acac)(3) as precursors. The surface silanol groups of SiO2 acted as the centers to interact with M(acac)(3) (M=Rh, Sm) molecules when SiO2 was impregnated in the M(acac)(3) solution, leading to the formation of a hydrogen-bonded M(acac)(3) layer on the SiO2 surface. In this experiment, the monolayer coverage of Sm(acac)(3) on the SiO2 surface was equal to a Sm(acac)(3) loading (mass fraction) of approximately 31%, which in turn corresponded to a Sm2O3 loading of approximately 15%. When a Sm(acac)(3)/SiO2 sample with Sm(acac)(3) loading below 31% was heated in air to approximately 360?, the monolayer Sm(acac)(3) species decomposed into highly dispersed Sm2O3 species on the SiO2 surface, which displayed superior stability against sintering at high temperature. No aggregation of the Sm2O3 species was observed even when the sample was heated to 800 degrees C in air. The strong interaction between the highly dispersed Sm2O3 and Rh plays a key role in increasing the dispersion of Rh species in the catalyst and preventing the Rh species from sintering under high temperature conditions. This factor should also be responsible for the superior activity and stability of the Rh-Sm2O3/SiO2 catalyst with extremely low Rh loading for the catalytic partial oxidation of methane to syngas.国家重点基础研究发展规划项目(2013CB933102),国家自然科学基金(21473144,21373168),国家基础科学人才培养基金项目(J1310024)及教育部创新研究团队项目(IRT_14R31)资
严重事故下蒸汽发生器传热管诱发破裂现象及其缓解策略分析
蒸汽发生器传热管是核反应堆冷却剂系统压力边界的重要组成部分,研究严重事故下蒸汽发生器传热管诱发破裂现象及其影响因素对支持二级概率安全分析意义重大.以CPR1000电厂全厂断电叠加蒸汽发生器安全阀卡开事故为基础事故序列,分析了轴封破口、环路水封清除和下降管水封清除现象对蒸汽发生器传热管诱发蠕变破裂现象的影响,并对二次侧卸压-补水和一次侧卸压-补水两种缓解策略的效果进行了研究.结果表明:轴封破口现象会影响逆向自然循环流量,但不会影响热管段和蒸汽发生器传热管发生蠕变破裂的先后顺序;而环路水封清除和下降管水封清除现象会打破热管段逆向自然循环现象,并导致蒸汽发生器传热管比其他冷却剂系统边界更早失效,从而带来安全壳旁通风险;而二次侧卸压-补水策略和一次侧卸压-补水策略都可以达到降低蒸汽发生器传热管诱发破裂风险的效果.该研究结果有助于改进二级概率安全分析结果,指导CPR1000电厂制定相关严重事故缓解措施并提升严重事故管理导则的事故处置能力.福建省科技厅计划项目(2016H0034);;厦门大学能源学院发展基金(2017NYFZ01
CPR1000全厂断电叠加小破口事故下一回路外部注水策略分析
严重事故管理导则(SAMGs)是目前缓解核电站严重事故进程的主要依据,而对反应堆一回路进行卸压和补水是严重事故下保证堆芯冷却最常用的策略,但是目前的SAMGs对于外部注水策略并没有给出具体的操作指导。所以,本研究以我国目前广泛应用的CPR1000核电站作为研究对象,以全厂断电叠加小破口事故作为基础事故序列,采用模块化严重事故分析程序对其进行建模,并对一回路外部注水策略进行了详细分析。结果表明,根据不同外部注水时间采取合适的卸压速率及注水流量可有效缓解事故进程,使堆芯冷却,防止压力容器失效,大量放射性外泄。该研究成果可为完善CPR1000核电站SAMGs中外部注水的具体措施以及核电厂类似序列的培训课程提供参考。厦门大学能源学院发展基金(2017NYFZ01
Ni和Ce前驱体对Ni-CeO2/SiO2催化剂的甲烷部分氧化制合成气性能的影响
以不同Ni和Ce的化合物为前驱体、商品SiO2为载体,采用浸渍法制备了一系列Ni/SiO2、CeO2/SiO2和Ni-CeO2/SiO2催化剂,对CeO2在SiO2载体上的分散情况进行了表征,在此基础上进一步探究了不同前驱体制备的CeO2/SiO2对Ni的稳定情况以及Ni-CeO2/SiO2催化剂的甲烷部分氧化(methane partial oxidation, POM)制合成气的反应性能,并考察了Ni物种与CeO2之间的相互作用。研究发现,以Ce(NO3)3或Ce(NO3)3添加柠檬酸(CA)制备的CeO2/SiO2样品的H2-TPR谱图中均同时出现了表面CeO2和体相CeO2物种的还原峰,而以Ce(CH3COO)3制备的CeO2/SiO2样品上则主要含表面CeO2物种。不同前驱体制备的1%Ni/SiO2催化剂的POM反应稳定性均较差。向1%Ni/SiO2中添加CeO2后,以硝酸盐或硝酸盐添加柠檬酸制备的1%Ni-10%CeO2/SiO2催化剂的POM反应稳定性均显著提高,说明相关样品上的CeO2物种可以较好地稳定催化剂上的Ni物种,防止其在反应条件下烧结。通过H2-TPR表征可知,对于以Ce(NO3)3或Ce(NO3)3添加柠檬酸制备的1%Ni-10%CeO2/SiO2催化剂,Ni物种的还原峰温均有所提高,说明相关样品上的CeO2与Ni物种之间存在较强的相互作用。而与以Ni(CH3COO)2为前驱体制备的1%Ni/SiO2相比,以Ni(CH3COO)2和 Ce(CH3COO)3为前驱体制备的1%Ni-10%CeO2/SiO2催化剂的POM反应稳定性并未得以显著改善,其原因可能是该催化剂上的CeO2与Ni物种之间的相互作用较弱,不利于稳定镍物种。国家自然科学基金(21473144,21872111)教育部创新研究团队项目(IRT_14R31
The Phylogeny Tree Reconstruction Based on the Usage Frequencyof Codons and Corresponding Complementary Codons
为了更深入地了解密码子与互补密码子使用相关的内涵,70个单细胞和多细胞生物被更进一步的分析。结果得到70种细胞生物具有较高的相关系数平均值(0.5101,标准差是0.1389),表明密码子与其互补密码子使用间确实存在正的使用相关联系,进一步地支持了以前的结果。此外,通过对70个单细胞和多细胞生物在基于密码子与互补密码子使用频率差异,以及配对频率的高低信息的分析基础上,绘制进化树,得到的进化树与传统的进化树非常接近。The hypothesis that a codon bias usage is identical to its complementary codon usage preference has been investigated by using the relationship analysis of codons vs their complementary ones among 70 organisms. Significantly positive usage correlations between codons and their complementary ones were found and its implication in biology was also analyzed. The codoncomplementary codon tree was further built, which fairly exhibited the evolutionary relationship of these organisms. The results not only demonstrated the validity of our hypothesis,but also manifested the usefulness of correlation analysis in studying on codon usage pattern and molecular evolutionary mechanisms of organism.ThisworkwassupportedbyagrantfromtheNationalNaturalScienceFoundationofChina(No.60305001)andagrantfromtheScienceandTechnologyMinistryofChina(PreliminaryStudyonFunctionalGenomeSystematics)(No.2001CCA01400)
铯添加对VO_x/SBA-15催化剂丙烷氧化脱氢性能影响
我们考察了碱金属铯的添加对具有单一活性中心(分立的VO4四面体)的VOx/SBA-15催化剂上丙烷氧化脱氢反应性能的影响,发现铯的加入可以显著改善丙烯的选择性.在相同的丙烷转化率时,丙烯选择性提高了约10%.对催化剂的X射线衍射,拉曼光谱,程序升温还原,吡啶吸附IR光谱和程序升温脱附表征结果表明,少量碱金属的加入,并未改变活性中心的结构及其可还原性能,但明显降低了催化剂表面酸量,尤其是B酸量,从而有利于产物丙烯的脱附,抑制了深度氧化产物COx的产生,提高了丙烯的选择性
The Molecular Evolution of Heat Shock Protein
热激蛋白是细胞内含量最丰富的蛋白质之一,在各种生物体内广泛分布.近年来对热激蛋白的研究已深入到结构、性质、功能等各面,其研究主要集中在:1)作为分子伴侣协助细胞内肽链的折叠;2)参与MHCⅠ类的分子呈递;3)使抗原通过内吞作用进入靶细胞;4)肿瘤免疫和分子疫苗开发.然而,虽然热激蛋白的研究已成为医学、生物学上的热点,其在分子进化上的研究也日渐增多,但这方面的报道仍然较少,本文主要从热激蛋白分子进化方面作一综述,这对理论研究、生物进化分析上都有着重要的意义.Heat shock proteins (hsps) are among the most abundant intracellular proteins.Certain hsps are able to:1) associate and chaperone a large variety of cellular peptides;2) be efficiently internalized by antigen presenting cells (APC) through receptormediated endocytosis;3) channel antigenic peptides they chaperone in the APC's MHC class I presentation pathway;4) act as molecular vaccine.Based on the ancient origins and structural conservation of hsps,there are more and more people studying on the molecular evolution of hsps.Though it ia still less known today,action of hsps as a molecular medium on studying evolution is significative
CPR1000全厂断电事故模拟及主泵轴封破口敏感性分析
全厂断电事故是导致核电厂发生严重后果的重要事件之一.采用模块化事故分析程序对CPR1000全厂断电事故进行建模与分析,计算一回路压力、压力容器水位、堆芯温度等参数,详细分析了事故进程.分析结果显示:全厂断电事故会导致反应堆压力容器在高压下失效,这将会有安全壳直接加热的风险;同时,事故过程中会产生大量氢气,这部分氢气会逐步迁移到安全壳或者辅助厂房中,从而带来氢气爆炸的风险.针对全厂断电时主泵容易出现轴封破口这一问题,选取了早、中、晚3个时期的事故序列,对轴封破口发生时间做敏感性分析.结果表明,早期破口会加速严重事故的进程,而较晚时间发生破口,尤其是事故中期发生破口能较好地延缓压力容器损毁进程.相关数据可为有关人员防范和缓解严重事故提供参考.福建省科技厅计划项目(2016H0034
CPR1000全厂断电叠加小破口失水事故下一回路外部注水策略分析
严重事故管理导则(SAMGs)是目前缓解核电站严重事故进程的主要依据,而对反应堆一回路进行卸压和注水是严重事故下保证堆芯冷却最常用的策略,但是目前的SAMGs对于外部注水策略并没有给出具体的操作指导.为此,以我国目前广泛应用的CPR1000核电站作为研究对象,以全厂断电叠加小破口失水事故作为基础事故序列,采用模块化严重事故分析程序对其进行建模,并对一回路外部注水策略进行了详细分析.结果表明,根据不同外部注水时间采取合适的卸压速率及注水流量可有效缓解事故进程,使堆芯冷却,防止压力容器失效及大量放射性物质外泄.该研究成果可为完善CPR1000核电站SAMGs中外部注水的具体措施以及核电厂类似事故序列的培训课程提供参考.厦门大学能源学院发展基金(2017NYFZ01