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Influence of Replacing Bacterial Pheophytin with Pheophytin on the Picosecond Fluorescence from Reaction Centers of Purple Bacteria 被引量:1
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作者 邹永龙 赵福利 +3 位作者 汪河洲 夏安东 曾小华 徐春和 《Acta Botanica Sinica》 CSCD 2000年第12期1243-1248,共6页
Fluorescence spectra of native purple bacterial reaction center (RC) and bacterial pheophytin (Bphe) replaced RCs were obtained from 600 nm to 900 nm with a selective excitation at 597 nm. With the help of measuring ... Fluorescence spectra of native purple bacterial reaction center (RC) and bacterial pheophytin (Bphe) replaced RCs were obtained from 600 nm to 900 nm with a selective excitation at 597 nm. With the help of measuring the fluorescence from bacterial chlorophyll, bacterial pheophytin and plant pheophytin, the corresponding components in the RCs are classified for fluorescence emission. Results showed that pheophytin substitution influences the composition of fluorescence spectra. Therefore, four, three and two components were obtained from fluorescence spectra of native RC, Bphe B_replaced RC and Bphe A,B _replaced RC, respectively. Fluorescence components are well correlated to the binding of plant pheophytin. The decay of excited state of primary electron donor P in different RCs was also studied by measuring the fluorescence decay at 686.4, 674.1 and 681.1 nm, respectively. The decaying kinetics changed in different RCs, indicating that pheophytin replacement influenced the energy transduction and primary photochemical reaction in purple bacterial reaction centers. 展开更多
关键词 pheophytin replacement picosecond fluorescence purple bacterial reaction center
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Incoherent Oscillations Accompanying Charge Separation in Photosynthetic Reaction Centers
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作者 A. G. Yakovlev V. A. Shuvalov 《Open Journal of Applied Sciences》 2013年第3期1-5,共5页
Early events of charge separation in reaction centers (RCs) of bacterial photosynthesis are modeled by kinetic equations with time-dependent rate constants. An illustrative case of regular motion along a “slow” coor... Early events of charge separation in reaction centers (RCs) of bacterial photosynthesis are modeled by kinetic equations with time-dependent rate constants. An illustrative case of regular motion along a “slow” coordinates leading to oscillations in the kinetics is examined. Different schemes of charge separation are investigated. A good fitting of experimental kinetics of native Rba. sphaeroides RCs is achieved in the five states model P*1BAHA&harr;P*2BAHA&harr;I&harr;P+HA&harr;P+BA with two excited states BAHA and BAHA and three charge separated states I, P+HA and P+BA (P is a primary electron donor, bacteriochlorophyll dimer, BA and HA are an electron acceptor, monomeric bacteriochlorophyll and bacteriopheophytin in active A-branch, respectively). In the model only the first excited state is directly populated by optical excitation. The emission of the two excited states is assumed to be at 905 and 940 nm, respectively. The intermediate state I is assumed to absorb at 1020 nm as well as the P+HA state. The model explains the deep oscillations in the kinetics of the stimulated emission and of the absorption. In the simpler schemes without the I state or with only one excited state the accordance with the experiment is achieved at unreal parameter values. A possible nature of the I and BAHA states and a possible incoherent nature of the oscillations are discussed. 展开更多
关键词 PHOTOSYNTHESIS CHARGE SEPARATION reaction center ELECTRON TRANSFER
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Cryo-electron microscopy structure of the intact photosynthetic light-harvesting antenna-reaction center complex from a green sulfur bacterium
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作者 Jing-Hua Chen Weiwei Wang +3 位作者 Chen Wang Tingyun Kuang Jian-Ren Shen Xing Zhang 《Journal of Integrative Plant Biology》 SCIE CAS CSCD 2023年第1期223-234,共12页
The photosynthetic reaction center complex(RCC)of green sulfur bacteria(GSB)consists of the membrane-imbedded RC core and the peripheric energy transmitting proteins called Fenna–Matthews–Olson(FMO).Functionally,FMO... The photosynthetic reaction center complex(RCC)of green sulfur bacteria(GSB)consists of the membrane-imbedded RC core and the peripheric energy transmitting proteins called Fenna–Matthews–Olson(FMO).Functionally,FMO transfers the absorbed energy from a huge peripheral light-harvesting antenna named chlorosome to the RC core where charge separation occurs.In vivo,one RC was found to bind two FMOs,however,the intact structure of RCC as well as the energy transfer mechanism within RCC remain to be clarified.Here we report a structure of intact RCC which contains a RC core and two FMO trimers from a thermophilic green sulfur bacterium Chlorobaculum tepidum at 2.9A resolution by cryo-electron microscopy.The second FMO trimer is attached at the cytoplasmic side asymmetrically relative to the first FMO trimer reported previously.We also observed two new subunits(PscE and PscF)and the N-terminal transmembrane domain of a cytochrome-containing subunit(PscC)in the structure.These two novel subunits possibly function to facilitate the binding of FMOs to RC core and to stabilize the whole complex.A new bacteriochlorophyll(numbered as 816)was identified at the interspace between PscF and PscA-1,causing an asymmetrical energy transfer from the two FMO trimers to RC core.Based on the structure,we propose an energy transfer network within this photosynthetic apparatus. 展开更多
关键词 cryo-electron microscopy energy transfer FMO protein green sulfur bacterium PHOTOSYNTHESIS reaction center
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Quantum Chemical Studies on Proteins in the Reaction Center of Rhodobacter sphaeroides 被引量:1
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作者 徐红 马淑华 +3 位作者 沈玲玲 张晓东 张兴康 张启元 《Acta Botanica Sinica》 CSCD 2001年第6期565-570,共6页
The electronic structure of protein chains L and M in photosynthetic reaction center (PRC) of Rhodobacter sphaeroides (Van Niel) Imhoff, Truper et Pfennig) was studied by using the Overlapping Dimer Approximation meth... The electronic structure of protein chains L and M in photosynthetic reaction center (PRC) of Rhodobacter sphaeroides (Van Niel) Imhoff, Truper et Pfennig) was studied by using the Overlapping Dimer Approximation method and the Extended Negative Factor Counter method at ab initio level. The result indicated that: (1) Amino acid residues, the molecular orbitals of which composed the main components of frontier orbitals of protein chain L (M), are located at the random coil areas of chain L (alpha helix areas of chain M). Since the random coil is flexible and more easy to change its conformation in the electron transfer process and to reduce the energy of the system, and the structure of the alpha helix is reletively stable, this difference might be one of the causes for the electron transfer in photosynthetic reaction center (PRC) only takes place along the L branch. (2) The His residues which axially coordinated to the 'special pair' P and accessory chlorophyll molecules (ABChls) are essentially important for the E-LUMO levels of P and ABChl. But, the corresponding molecular orbitals of these His residues do not appear in the composition of frontier orbitals of protein chains. It means that the interaction between pigment molecules and protein chains do not influence the contribution to the frontier orbitals of protein chains explicitly, but influences the corresponding E-LUMO levels significantly. 展开更多
关键词 photosynthetic reaction center Rhodobacter sphaeroides electronic structure of protein ab initio Extended Negative Factor Counter method (ENFC)
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A unique photosystem I reaction center from a chlorophyll d-containing cyanobacterium Acaryochloris marina 被引量:1
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作者 Caihuang Xu Qingjun Zhu +9 位作者 Jing-Hua Chen Liangliang Shen Xiaohan Yi Zihui Huang Wenda Wang Min Chen Tingyun Kuang Jian-Ren Shen Xing Zhang Guangye Han 《Journal of Integrative Plant Biology》 SCIE CAS CSCD 2021年第10期1740-1752,共13页
Photosystem I(PSI)is a large protein supercomplex that catalyzes the light-dependent oxidation of plastocyanin(or cytochrome c6)and the reduction of ferredoxin.This catalytic reaction is realized by a transmembrane el... Photosystem I(PSI)is a large protein supercomplex that catalyzes the light-dependent oxidation of plastocyanin(or cytochrome c6)and the reduction of ferredoxin.This catalytic reaction is realized by a transmembrane electron transfer chain consisting of primary electron donor(a special chlorophyll(Chl)pair)and electron acceptors A_(0),A_(1),and three Fe_(4)S_(4) clusters,F_(X),F_(A),and F_(B).Here we report the PSI structure from a Chl d-dominated cyanobacterium Acaryochloris marina at 3.3Åresolution obtained by single-particle cryo-electron microscopy.The A.marina PSI exists as a trimer with three identical monomers.Surprisingly,the structure reveals a unique composition of electron transfer chain in which the primary electron acceptor A_(0) is composed of two pheophytin a rather than Chl a found in any other well-known PSI structures.A novel subunit Psa27 is observed in the A.marina PSI structure.In addition,77 Chls,13α-carotenes,two phylloquinones,three Fe-S clusters,two phosphatidyl glycerols,and one monogalactosyl-diglyceride were identified in each PSI monomer.Our results provide a structural basis for deciphering the mechanism of photosynthesis in a PSI complex with Chl d as the dominating pigments and absorbing far-red light. 展开更多
关键词 A.marina chlorophyll d cryoelectron microscopy pheophytin a PHOTOSYNTHESIS photosystem I reaction center
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Reconstitution of Photosystem Ⅱ Reaction Center with Cu-ChlorophyⅡ a
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作者 Shuang Liu Feng-Qin Dong Chun-Hong Yang Chong-Qin Tang Ting-Yun Kuang 《Journal of Integrative Plant Biology》 SCIE CAS CSCD 2006年第11期1330-1337,共8页
An Isolated photosystem (PS) II reaction center (RC) with altered pigment content was obtained by chemical exchange of native chlorophyll a (Chl) with externally added Cu-Chl a (Cu-Chl). Pigment composition an... An Isolated photosystem (PS) II reaction center (RC) with altered pigment content was obtained by chemical exchange of native chlorophyll a (Chl) with externally added Cu-Chl a (Cu-Chl). Pigment composition and spectroscopic properties of the RC exchanged with Cu-Chl were compared with native RC and RC treated with Chl In the same way. High-performance liquid chromatography analysis showed approximately 0.5 Cu-Chl per two pheophytln in the Cu-Chl-reconstltuted RC preparation. Insertion of Cu-Chl resulted in a decrease In absorption at 670 nm and an Increase at 660 nm, suggesting that the peripheral Chl may have been displaced. Fluorescence emission spectra of the Cu-Chl-reconstituted RC displayed a marked decrease In fluorescence yield and a blue shift of the band maximum, accompanied by the appearance of a broad peak at a shorter wavelength, Indicating that energy transfer In the modified RC was disturbed by Cu-Chl, a quencher of the excited state. However, there were few differences in the circular dichrolsm (CD) spectra, suggesting that the arrangement of pigments and proteins responsible for the CD signal was not significantly affected. In addition, no obvious change In peptlde components was found after the exchange procedure. 展开更多
关键词 Cu-chlorophyⅡ a photosystem reaction center reconstitution.
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Structural Changes of Water Molecules Upon the Reduction of Quinones in The Reaction Center from Rhodobactery Sphaeroides
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作者 T.Iwata M.L.Paddock +1 位作者 M.Y.Okamura H.Kandori 《复旦学报(自然科学版)》 CAS CSCD 北大核心 2007年第5期589-,共1页
1 Results The photosynthetic bacterial reaction center (RC) is a membrane protein complex.The RC is composed of three protein subunits and redox components such as bacteriochlorophylls, bacteriopheophytins,and quinone... 1 Results The photosynthetic bacterial reaction center (RC) is a membrane protein complex.The RC is composed of three protein subunits and redox components such as bacteriochlorophylls, bacteriopheophytins,and quinones.The RC performs the photochemical electron transfer from the bacteriochlorophyll dimer through a series of electron donor and acceptor molecules to a secondary quinone,QB.QB accepts electrons from a primary quinone,QA,in two sequential electron transfer reactions.The second electron trans... 展开更多
关键词 photosynthetic reaction center proton uptake FTIR spectroscopy
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Involvement of DEG5 and DEG8 proteases in the turnover of the photosystem II reaction center D1 protein under heat stress in Arabidopsis thaliana 被引量:6
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作者 SUN XuWu WANG LiYuan ZHANG LiXin 《Chinese Science Bulletin》 SCIE EI CAS 2007年第13期1742-1745,共4页
Deg5,deg8 and the double mutant,deg5deg8 of Arabidopsis thaliana were used to study the physiological role of the DEG proteases in the repair cycle of photosystem II (PSII) under heat stress. PSII activity in deg muta... Deg5,deg8 and the double mutant,deg5deg8 of Arabidopsis thaliana were used to study the physiological role of the DEG proteases in the repair cycle of photosystem II (PSII) under heat stress. PSII activity in deg mutants showed increased sensitivity to heat stress, and the extent of this effect was greater in the double mutant, deg5deg8, than in the single mutants, deg5 and deg8. Degradation of the D1 protein was slower in the mutants than in the WT plants. Furthermore, the levels of other PSII reaction center proteins tested remained relatively stable in the mutant and WT plants following high-temperature treatment. Thus, our results indicate that DEG5 and DEG8 may have synergistic function in degradation of D1 protein under heat stress. 展开更多
关键词 D1蛋白 蛋白酶 阿布属 光合作用
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Magnetic circular dichroism of photosystem Ⅱ reaction center complex 被引量:1
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作者 YANG Kunyun, TANG Chongqin, KUANG Tingyun, TANG Peisong, SHEN Ziwei, LIN Wei, ZHANG Xiufang and ZHAO Nanming1 Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China 2. State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsmghua University, Beijing 100084, China 《Chinese Science Bulletin》 SCIE EI CAS 1997年第9期784-787,共4页
IN recent years,magnetic circular dichroism(MCD)demonstrated its unique advantages inanalysis of metal porphyrin and its interaction with protein.However,there were few re-ports about the application of MCD method in ... IN recent years,magnetic circular dichroism(MCD)demonstrated its unique advantages inanalysis of metal porphyrin and its interaction with protein.However,there were few re-ports about the application of MCD method in photosynthesis field.It is known that most pig-ments in PS Ⅱ-RC are metal porphyrin type.This note reports the MCD spectrum of PS Ⅱ- 展开更多
关键词 PHOTOSYSTEM reaction center MAGNETIC CIRCULAR dichroism.
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Replacement of bacteriopheophytin in reaction centers from Rhodobacter sphaeroides RS601 with plant pheophytin 被引量:1
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作者 曾小华 吴永强 +1 位作者 沈允钢 徐春和 《Science China(Life Sciences)》 SCIE CAS 2000年第1期21-29,共9页
In the presence of acetone and an excess of exogenous plant pheophytins, bacterio-pheophytins in the reaction centers from Rhodobacter sphaeroides RS601 were replaced by pheophytins at sites HA and HB, when incubated ... In the presence of acetone and an excess of exogenous plant pheophytins, bacterio-pheophytins in the reaction centers from Rhodobacter sphaeroides RS601 were replaced by pheophytins at sites HA and HB, when incubated at 43.5℃ for more than 15 min. The substitution of bacteriopheophytins in the reaction centers was 50% and 71% with incubation of 15 and 60 min, respectively. In the absorption spectra of pheophytin-replaced reaction centers (Phe RCs), bands assigned to the transition moments Qx (537 nm) and QY (758 nm) of bacteriopheophytin disappeared, and three distinct bands assigned to the transition moments Qx (509/542 nm) and QY (674 nm) of pheophytin appeared instead. Compared to that of the control reaction centers, the photochemical activities of Phe RCs are 78% and 71% of control, with the incubation time of 15 and 60 min. Differences might exist between the redox properties of Phe RC and of native reaction centers, but the substitution is significant, and the new system is available for further studies. 展开更多
关键词 bacterial-photosynthetic reaction center PHEOPHYTIN PIGMENT REPLACEMENT activity of LIGHT-INDUCED electron transfer.
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Theoretical studies on the influence of molecular interactions on the mechanism of electron transfer in photosynthetic reaction center of Rps.viridis
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作者 徐红 张兴康 +2 位作者 张汝波 张启元 屈正旺 《Science China Chemistry》 SCIE EI CAS 2002年第6期570-585,共16页
Based on the QM/MM optimized X-ray crystal structure of the photosynthetic reaction center (PRC) of purple bacteria Rhodopseudomonas (Rps.) viridis, quantum chemistry density functional method (DFT, B3LYP/6-31G) has b... Based on the QM/MM optimized X-ray crystal structure of the photosynthetic reaction center (PRC) of purple bacteria Rhodopseudomonas (Rps.) viridis, quantum chemistry density functional method (DFT, B3LYP/6-31G) has been performed to study the interactions between the pigment molecules and either the surrounded amino acid residues or water molecules that are either axially coordinated or hydrogen bonded with the pigment molecules, leading to an explanation of the mechanism of the primary electron-transfer (ET) reactions in the PRC. Results show that the axial coordination of amino acid residues greatly raises the ELUMO of pigment molecules and it is important for the possibility of ET to take place. Different hydrogen bonds between amino acid residues, water molecules and pigment molecules decrease the ELUMO of the pigment molecules to different extents. It is crucial for the ET taking place from excited P along L branch and sustains that the ET is a one-step reaction without through accessory bacteriochlorophyll (ABChl b). It is insufficient to treat the whole protein surrounding as a homogeneous dielectric medium. 展开更多
关键词 bacteria PHOTOSYNTHETIC reaction center electron transfer PIGMENT molecule interaction between PIGMENT MOLECULES and neighboring AMINO acid residue DFT.
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单侧负重对足底压力和稳定性的影响研究
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作者 李波 金钊 +1 位作者 宋宁 李国英 《皮革科学与工程》 CAS 北大核心 2024年第3期80-85,共6页
单手提重物在日常生活和工作中很常见,不对称负重不仅增大下肢载荷,而且使人-手提物重心偏离正中矢状面,可能导致足底水泡、应力性骨折和摔跤风险增大。用1 m的压力板测量了15名健康男性大学生分别手提7 kg和14 kg重的包行走时的垂直地... 单手提重物在日常生活和工作中很常见,不对称负重不仅增大下肢载荷,而且使人-手提物重心偏离正中矢状面,可能导致足底水泡、应力性骨折和摔跤风险增大。用1 m的压力板测量了15名健康男性大学生分别手提7 kg和14 kg重的包行走时的垂直地面反作用力和足底压力中心,用1 m的测力台测量静止站立30 s时的地面反作用力,以此为依据分析单侧负重对人体稳定性、足部冲击和步态的影响。结果表明,在实验的两种负重时,足底压力绝对值增大,相对值不变,稳定性降低,步态改变。针对经常性单侧负重群体的功能鞋设计,需要增大鞋底缓冲性能以减小损伤,增加鞋类稳定性以减小摔跤风险。 展开更多
关键词 单侧负重 稳定性 地面反作用力 足底压力中心
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紫色光合细菌LH1-RC复合物的结构生物学研究进展
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作者 岳星宇 王征宇 于龙江 《自然杂志》 CAS 2024年第1期23-34,共12页
紫色光合细菌作为研究光合作用分子机制的一种古老的模式生物,通过无氧光合作用将太阳能转化为化学能,其光合作用原初反应主要发生在由捕光天线复合物1(LH1)及反应中心复合物(RC)组成的核心复合物(LH1-RC)中。近年来,随着晶体学和冷冻... 紫色光合细菌作为研究光合作用分子机制的一种古老的模式生物,通过无氧光合作用将太阳能转化为化学能,其光合作用原初反应主要发生在由捕光天线复合物1(LH1)及反应中心复合物(RC)组成的核心复合物(LH1-RC)中。近年来,随着晶体学和冷冻电镜技术的迅速发展,多个不同菌种来源的LH1-RC复合物的三维结构被解析出来,极大地拓展了人们对该复合物的认识。文章系统总结了近年来紫细菌光合膜蛋白复合物的结构生物学研究进展,为深入了解光合作用分子机制、提高光合效率、促进人工光合作用系统的开发及应用提供了理论基础。 展开更多
关键词 光合作用 紫色光合细菌 捕光天线复合物 反应中心复合物 核心复合物
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Low H_(2)O_(2)consumption Fenton-like catalysts for pollutant cleavage based on the construction of a dual reaction center
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作者 Weixiang Liao Ziwen Zhao +2 位作者 Lai Lyu Chun Hu Fan Li 《Journal of Environmental Sciences》 SCIE EI CAS 2024年第11期107-116,共10页
High energy consumption has seriously hindered the development of Fenton-like reactions for the removal of refractory organic pollutants in water.To solve this problem,we designed a novel Fenton-like catalyst(Cu-PAN3)... High energy consumption has seriously hindered the development of Fenton-like reactions for the removal of refractory organic pollutants in water.To solve this problem,we designed a novel Fenton-like catalyst(Cu-PAN3)by coprecipitation and carbon thermal reduction.The catalyst exhibits excellent Fenton-like catalytic activity and stability for the degradation of various pollutants with low H_(2)O_(2)consumption.The experimental results indicate that the dual reaction centers(DRCs)are composed of Cu-N-C and Cu-O-C bridges between copper and graphene-like carbon,which form electron-poor/rich centers on the catalyst surface.H_(2)O_(2)is mainly reduced at electron-rich Cu centers to free radicals for pollutant degradation.Meanwhile,pollutants can be oxidized by donating electrons to the electron-poor C centers of the catalyst,which inhibits the ineffective decomposition of H_(2)O_(2)at the electron-poor centers.This therefore significantly reduces the consumption of H_(2)O_(2)and reduces energy consumption. 展开更多
关键词 Water purification Fenton-like Dual reaction centers Graphene-like carbon Low H_(2)O_(2)consumption
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分子筛催化反应过程高效化的技术进展
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作者 王达锐 孙洪敏 +4 位作者 王一棪 唐智谋 李芮 范雪研 杨为民 《化工进展》 EI CAS CSCD 北大核心 2024年第1期1-18,F0003,共19页
以分子筛为活性组分制成的催化剂广泛应用于石油化工领域。设计开发高效能的分子筛催化剂来实现化学反应过程高效化,可为化工企业节能降耗和降本增效提供技术支撑。种类繁多的催化反应对分子筛提出了不同的需求,本文从四个方面综述了开... 以分子筛为活性组分制成的催化剂广泛应用于石油化工领域。设计开发高效能的分子筛催化剂来实现化学反应过程高效化,可为化工企业节能降耗和降本增效提供技术支撑。种类繁多的催化反应对分子筛提出了不同的需求,本文从四个方面综述了开发高效分子筛的技术进展,包括硅铝分子筛酸性活性中心调变和钛硅分子筛Ti活性中心构建的活性中心修饰方案、微孔分子筛内部造介孔和介孔SiO2包覆分子筛的孔道结构调变方案、制备纳米级颗粒和控制择向性生长的晶体形貌控制方案、创制新结构分子筛的拓扑结构创新方案,探讨了分子筛催化剂的未来发展方向,指出我国仍需在该领域持续加强技术创新,尤其是原始创新,做到产学研深度结合,将先进技术转化为可实际操作的方案,最终服务于生产装置、实现工业应用是提高石油化工技术进步的重点工作。 展开更多
关键词 分子筛 催化剂 多相反应 活性中心 孔道结构 晶体形貌 新型结构
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Ru/AC和Ru-NPs/AC催化剂对乙炔氢氯化反应催化活性的比较
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作者 徐达 王赛赛 +4 位作者 马腾云 万立祺 赵佳 蔡海婷 李小年 《高校化学工程学报》 EI CAS CSCD 北大核心 2024年第4期578-585,共8页
针对乙炔氢氯化反应无汞催化剂的开发,Ru基催化剂是最具工业潜力的催化剂之一。结合表面积分析仪(BET)、程序升温还原(TPR)、透射电镜(TEM)和程序升温脱附(TPD),以及动力学实验探究了导致Ru/AC(AC为活性炭)和高温H_(2)处理后Ru-NPs/AC... 针对乙炔氢氯化反应无汞催化剂的开发,Ru基催化剂是最具工业潜力的催化剂之一。结合表面积分析仪(BET)、程序升温还原(TPR)、透射电镜(TEM)和程序升温脱附(TPD),以及动力学实验探究了导致Ru/AC(AC为活性炭)和高温H_(2)处理后Ru-NPs/AC催化性能差异的原因。在排除内、外扩散的条件下,通过动力学实验判断了反应级数,初步推测了基元反应步骤和决速步骤。结果表明,Ru-NPs/AC相对于Ru/AC总反应速率更低,表观活化能更高,这是由于高温H_(2)处理后活性组分的分散度降低、Ru物种被还原,并且导致活性中心对C_(2)H_(2)的吸附性能降低。 展开更多
关键词 乙炔氢氯化 Ru基催化剂 反应级数 表观活化能 活性中心
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磷掺杂碳负载Zn_(x)P_(y)O_(z)常温常压下高效电催化合成氨
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作者 王佳 秦清 +5 位作者 王哲 赵旭浩 陈云菲 候利强 刘尚果 刘希恩 《物理化学学报》 SCIE CAS CSCD 北大核心 2024年第3期29-30,共2页
合成氨(NH_(3))的发展是现代工业进程和人类生存的基石。受氮气(N_(2))化学惰性的限制,当前的合成氨工业能源消耗高并且排放大量的二氧化碳。电化学氮气还原反应(NRR),是有望取代高能耗的Haber-Bosch(HB)合成法的一种绿色可持续的合成... 合成氨(NH_(3))的发展是现代工业进程和人类生存的基石。受氮气(N_(2))化学惰性的限制,当前的合成氨工业能源消耗高并且排放大量的二氧化碳。电化学氮气还原反应(NRR),是有望取代高能耗的Haber-Bosch(HB)合成法的一种绿色可持续的合成氨工艺。然而,因氮气以及析氢竞争富反应(HER)导致电催化氮气还原极低的NH_(3)产率和能量转换效率一直是目前人工固氮领域面临的挑战。在本文中,我们报道了一种具有丰富孔结构的磷掺杂碳(PC)负载Zn_(3)(PO_(4))_(2)/Zn_(2)P_(2)O_(7)纳米复合材料(h-PC/Zn_(3)(PO_(4))_(2)/Zn_(2)P_(2)O_(7)),在酸性和中性介质中将N_(2)高效催化转化为NH_(3)。其独特的分级多孔结构提高了表面粗糙度并加快了氮气在催化剂体相中的扩散,这有利于延长氮气在催化剂表面的停留时间以及提高活性位点的利用效率。而多组分的均匀分布可以调节电子结构并优化反应中间体的吸附行为,进而提高活性位点的本征活性。在0.1mol·L^(-1)HCI电解液中,h-PC/Zn_(3)(PO_(4))_(2)/Zn_(2)P_(2)O_(7)在-0.2 V vs.可逆氢电极(RHE)电位下NH_(3)的产率可以达到38.7±1.2μg·h^(-1)·mgcat^(-1),法拉第效率为19.8%±0.9%。此外;h-PC/Zn_(3)(PO_(4))_(2)/Zn_(2)P_(2)O_(7)在0.1 mol·L^(-1)Na_(2)SO_(4)溶液中同样展现出优异的电催化氮气还原合成氨性能,NH_(3)产率及法拉第效率分别为17.1±0.8μg·h^(-1)·mgcat^(-1)和15.g%±0.6%,明显优于PC/Zn_(3)P_(2)、C/ZnO和大多数报道的非贵金属电催化剂。这种优异的性能主要归因于多孔结构有利于传质及多组分活性位点协同效应。此外,我们采用非原位X射线光电子能谱(XPS)、透射电子显微镜(TEM)和X射线衍射(XRD)等表征手段对NRR测试前后h-PC/Zn_(3)(PO_(4))_(2)/Zn_(2)P_(2)O_(7)的组成和结构变化进行了剖析。在反应后检测到了新增的N物种信号,证明催化剂确实发生了氮气还原反应。本研究提供了一种通过同步构建传质通道并耦合不同的活性位点以协同增强NRR活性和选择性的新思路,这对加快绿色制氨工业化具有重大意义。 展开更多
关键词 氮气还原反应 电催化剂 孔结构 多活性中心 协同效应
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在硫化钼基面上调控原子级协同活性中心用于碱氢演化反应
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作者 罗旭宇 王颖 +4 位作者 杨光 刘璐 郭诗颖 崔义 许小勇 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第6期281-290,共10页
电解水技术是一种生产高纯氢燃料的方法,能够增强可再生能源发电系统的消纳能力.相较于质子交换膜(PEM)电解槽,碱性(ALK)电解槽可以使用非贵金属基催化电极,拥有更高的经济效益和市场占有率.然而,由于ALK电解槽处于质子稀缺环境,阴极氢... 电解水技术是一种生产高纯氢燃料的方法,能够增强可再生能源发电系统的消纳能力.相较于质子交换膜(PEM)电解槽,碱性(ALK)电解槽可以使用非贵金属基催化电极,拥有更高的经济效益和市场占有率.然而,由于ALK电解槽处于质子稀缺环境,阴极氢气演化反应(HER)动力学变得更加复杂,需要快速解离水分子提供动态质子微环境.硫化钼(MoS_(2))纳米片边缘具有合适的质子吸附和演化的活性位点,是制备HER催化剂的潜力材料.但其二维基面原子由于配位饱和,显示出较弱的质子吸附能力.如何调控MoS_(2)基面以实现水解动力与质子吸附演化动力的集成,提升MoS_(2)纳米片的碱性HER活性,具有重要的科学和应用意义.本文提出了一种Co/O双原子植入策略,精准调控双活性位点及其电子结构,实现了水解离动力和质子吸附演化动力的高效耦联.首先,利用刻蚀和电沉积的两步实验法,在MoS_(2)基面上成功引入O和Co原子;随后,结合高分辨透射电镜、高角环形暗场-扫描透射电子显微镜、同步辐射X射线吸收精细结构谱等表征分析技术,精准识别了掺杂Co/O原子的位置和配位情况:O原子替换部分S原子,Co原子占据Mo原子的上方,构建出立体凸起的“O-Co-S_(2)”配位构型.催化在线的原位表征分析结果表明:该独特的“O-Co-S_(2)”原子基序发挥着水解离与氢演化反应协同催化效应.密度泛函理论计算结果也证实了该协同机制,其中Co位点促进水的解离反应,而S位点则有助于质子的转化生成氢气.因此,Co/O掺杂MoS_(2)催化剂(Co-O@MoS_(2))表现出较好的碱性HER活性:仅需81 mV的过电位,即可达到100 mA cm^(‒2)的电流密度,Tafel斜率低至42 mV dec^(‒1),在600 mA cm^(‒2)的高电流密度测试中运行300 h活性无衰减.上述碱性HER性能不仅远高于原始的MoS_(2)纳米片,而且也领先于部分已报道结果.综上所述,本文在MoS_(2)基面上构筑了原子级协同催化活性中心,显著促进了碱性HER反应性能,为原子活化工程开发先进催化剂提供参考,在原子级基序构造、表征和功能分析方面提供借鉴. 展开更多
关键词 碱水电解 氢气演化反应 硫化钼 原子尺度活化 协同活性位点
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国家会展中心(天津)一期项目防水设计与施工 被引量:1
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作者 刘涛 徐策 +2 位作者 杨建国 沈凯 杨晓虹 《中国建筑防水》 2024年第3期47-49,共3页
国家会展中心(天津)一期项目地下室防水采用1.5 mm厚高分子反应粘交叉膜防水卷材(单面粘)+1.5 mm厚高分子反应粘交叉膜防水卷材(双面粘)湿铺法施工,桩头部位采用水泥基渗透结晶型防水涂料密封处理,施工过程中质量管理严格,取得了良好的... 国家会展中心(天津)一期项目地下室防水采用1.5 mm厚高分子反应粘交叉膜防水卷材(单面粘)+1.5 mm厚高分子反应粘交叉膜防水卷材(双面粘)湿铺法施工,桩头部位采用水泥基渗透结晶型防水涂料密封处理,施工过程中质量管理严格,取得了良好的防水效果。 展开更多
关键词 国家会展中心 地下室防水 高分子反应粘交叉膜防水卷材 水泥基渗透结晶型防水涂料
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药师管理在静脉药物配置中心抗肿瘤药物合理使用中的实施效果评价
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作者 柯妍妍 周海胜 车华燕 《智慧健康》 2024年第21期141-143,147,共4页
目的 分析药师管理在静脉药物配置中心抗肿瘤药物合理使用中的实施效果。方法 选择2023年1月—2023年6月在静脉药物配置中心配置的抗肿瘤药物医嘱5684份进行研究,使用随机数法将其分为观察组(2842份)和对照组(2842份)。其中,对照组使用... 目的 分析药师管理在静脉药物配置中心抗肿瘤药物合理使用中的实施效果。方法 选择2023年1月—2023年6月在静脉药物配置中心配置的抗肿瘤药物医嘱5684份进行研究,使用随机数法将其分为观察组(2842份)和对照组(2842份)。其中,对照组使用常规药师管理,观察组使用审方药师严格审核管理,比较管理后的不合理医嘱率、不合理医嘱分布类型及用药不良反应发生率。结果 管理后,观察组的不合理医嘱率低于对照组(P<0.05);管理后,观察组的不合理医嘱分布类型评分低于对照组(P<0.05);管理后,观察组的用药不良反应发生率低于对照组(P<0.05)。结论 在静脉药物配置中心中应用审方药师严格审核管理可以有效降低不合理医嘱率、不合理医嘱分布类型及用药不良反应发生率,值得在静脉药物配置中心管理中应用。 展开更多
关键词 静脉药物配置中心 抗肿瘤药物 用药不良反应发生率
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