丝氨酸蛋白酶中催化三元组内氢键的作用（英文）

为了探究丝氨酸蛋白酶催化效率的来源,本文分别研究了丝氨酸酶催化水解多肽CI2、MCTI-A和六肽(SUB)的过程中催化三元组内的氢键所起的作用.首先采用QM/MM-MD方法计算了在酶-底物复合物和过渡态下组氨酸和天冬氨酸之间质子转移的自由能曲线.结果表明低能垒氢键仅在CI2酰化反应的过渡态区域形成,而在MCTIA和SUB酰化反应中均是正常氢键.与MCTI-A相比,CI2和SUB体系中氢键强度在过渡态时显著增强,因此相应的酰化反应能垒明显降低.过渡态区域形成的低能垒氢键显然有助于加速酰化反应,同时研究也表明正常氢键也有可能降低能垒.氢键降低能垒的关键则在于过渡态下氢键强度的增加程度,而不是其是否生成了低能垒氢键.本文为研究催化三元组间的氢键在丝氨酸蛋白酶中的作用提供了新思路,并有助于理解丝氨酸蛋白酶中催化三元组的催化机制.     

丝氨酸蛋白酶中催化三元组内氢键的作用

为了探究丝氨酸蛋白酶催化效率的来源,本文分别研究了丝氨酸酶催化水解多肽CI2、MCTI-A和六肽(SUB)的过程中催化三元组内的氢键所起的作用. 首先采用QM/MM-MD方法计算了在酶-底物复合物和过渡态下组氨酸和天冬氨酸之间质子转移的自由能曲线. 结果表明低能垒氢键仅在CI2酰化反应的过渡态区域形成,而在MCTI-A和SUB酰化反应中均是正常氢键. 与MCTI-A相比,CI2和SUB体系中氢键强度在过渡态时显著增强,因此相应的酰化反应能垒明显降低. 过渡态区域形成的低能垒氢键显然有助于加速酰化反应,同时研究也表明正常氢键也有可能降低能垒. 氢键降低能垒的关键则在于过渡态下氢键强度的增加程度,而不是其是否生成了低能垒氢键. 本文为研究催化三元组间的氢键在丝氨酸蛋白酶中的作用提供了新思路,并有助于理解丝氨酸蛋白酶中催化三元组的催化机制.     

Amplitude-N-power squeezing of pure superposition states

The N-order squeezing of the pure superposition states |a,β>_(mn)=a|m> β|n> is studied. We find that there is only N=n—m order squeezing for odd (n—m) except for (n—m)=1(m≥1) , but there are N=n—m order and N=(n—m)/2 order squeezings for even (n—m).     

叶栅正交和局部正交贴体网格的生成方法及其应用

一、二维叶栅正交O型网格的系列保角变换法 1.基本变换过程 变换公式和过程见图1。 在由Ω向ω的变换中,为求待定复常数a、b、c,先令ω(z=±∞)=±1,并定义Ω~+=[g(+∞)]~(1/k),Ω~-=[g(—∞)]~(1/k),由变换ω=(a—bΩ/c)/(1—Ω/c)得b=(—2c+Ω~-+Ω~+)/(Ω~+—Ω~-);a=1—(1—b)Ω~+/c;若r_(max)、r_(min)分别表示边界的最大、最小极径,则求常数c的迭代式为     

LATTICE QUANTUM CHROMODYNAMICS

<正>Updated September 2013 by S.Hashimoto(KEK),J.Laiho(Syracuse University),and S.R.Sharpe(University of Washington).18.1.Lattice regularization of QCD Gauge theories form the building blocks of the Standard Model.While the SU(2)and U(l)parts have weak couplings and can be studied accurately with perturbative methods,the SU(3)component—QCD—is only amenable to a perturbative treatment at high energies.The growth of the coupling constant in the infrared—the flip-side of asymptotic freedom—requires the use of non-perturbative methods to determine the low energy properties of QCD.Lattice gauge theory,proposed by K.Wilson in 1974[1],provides such a method,for it gives a non-perturbative definition of vector-like gauge field theories like QCD.In lattice regularized QCD—commonly called lattice QCD or LQCD—Euclidean space-time is discretized,usually on a hypercubic     

A device model for thin silicon-on-insulator SiGe heterojunction bipolar transistors with saturation effects

In this paper, we describe the saturation effect of a silicon germanium (SiGe) heterojunction bipolar transistor (HBT) fabricated on a thin silicon-on-insulator (SOI) with a step-by-step derivation of the model formulation. The collector injection width, the internal base—collector bias, and the hole density at the base—collector junction interface are analysed by considering the unique features of the internal and the external parts of the collector, as they are different from those of a bulk counterpart.     

运用运动图像探究运动的追及和相遇问题

运动图像有位移—时间图像(s—t图像)和速度—时间图像(v—t图像),明确两图像及物理意义,可巧妙解决许多问题.一、运动图像及物理意义1、位移—时间图像(s—t图像)在图中,a图线—加速运动图线,     

SUBJECT INDEX TO VOLUME 1, 2003

AbsorDtion Bragg suppression for optical absorptionin multi一(】uantum well structures.299 Cavity enhanced absorption spec—troscopy for N20 detection at 2.86Ⅲnusing a continuous tunable color center1aser.361Acousto—optical materials A high—speed automatic spectrome—ter})ased on a solid—state non—collinearacousto—optic tunable filter,85Air pollution monitoring A new differential absorption lidar forN02 nleasure~lents using Raman—shiftedtechnique,435Algebraic optical processing A rl…     

Y_3Fe_(5-x)Mn_xO_(12)的磁结构和磁性能

对多晶Y_3Fe_(5-x)Mn_xO_(12)(x=0.05和0.09),得到300K下的中子衍射曲线。发现当x=0.05时,Mn~(3+)离子占据16a和24d位置的几率分别为0.72和0.28;当x=0.09时,Mn~(3+)离子全部占据16a位置;还得到两种组分16a和24d位置各自的磁矩值。 在外磁场(800—10KOe)下测量Y_3Fe_(5-x)Mn_xO_(12)(x=0—0.11)的磁化曲线,温度范围是1.5—300K。得到饱和磁矩值;并利用趋近饱和定律确定1.5K下的磁晶各向异性常数k_1值,发现|K_1|值随含锰量增加而减小。     

AUGMENTATION OF EVOKED POTENTIALS FROM THE GUINEA PIG AUDITORY CORTEX AFTER EXPOSURE TO INTENSIVE NOISE

Evoked potential recorded from the guinea pig auditory cortex in response to high-intensityclicks was found to be systematically augmented as a result of exposure to noise in appropriatedosage which caused a moderate temporal response-threshold shift(16—48 dB,5—20 min afterexposure).The maximum post-exposure response amplitude might exceed the pre-exposure valueby 30—120%.No parallel amplitude increment was observed in cochlear potential and in evokedpotentials from the medial geniculate body,a fact indicating the cortical site of the mechanism under-lying such augmentation.     

Resolution of ghost imaging with entangled photons for different types of momentum correlation

We present an analytical analysis of the spatial resolution of quantum ghost imaging implemented by entangled photons from a general, spontaneously parametric, down-conversion process. We find that the resolution is affected by both the pump beam waist and the nonlinear crystal length. Hence, we determined a method to improve the resolution for a certain imaging setup. It should be noted that the resolution is not uniquely related to the degree of entanglement of the photon pair since the resolution can be optimized for a certain degree of entanglement. For certain types of Einstein-Podolsky-Rosen(EPR) states——namely the momentum-correlated or momentum-positively correlated states——the resolution exhibits a simpler relationship with the pump beam waist and crystal length. Further, a vivid numerical simulation of ghost imaging is presented for different types of EPR states,which supports our analysis. This work discusses applicable references to the applications of quantum ghost imaging.     

中国物理学会及所属分支机构2006年活动计划

序号活动类别活动名称主要内容时间(规人模)地点联系人电话及电子邮件1 a第三届中日原子级别表征学术研讨会(电子显微镜分会)学术交流3月6—10日50厦门柳得鲁北京科技大学,62334777,dlliu@vip.sina.com2 b,a中国物理学会相图专业委员会年度会议(相图专业委员会)委员会年度工作安排,学术交流4—6月30待定杜振民北京科技大学,62333772,zmdu2@hotmail.com3 a第六届中日核物理研讨会(核物理分会)研讨滴线核的结构和反应,超重核素,;超核,核天体物理等领域的最新成果5月15—20日100上海马余刚中科院上海应用物理研究所,021-59554780,ygma@sinap.ac…     

摄影光学 高速摄影及其装置

TB853.17 2004053721 高速相机数据记录系统的改进=Improvement of the data recording system of a high-speed camera[刊,中]/李变侠(中科院西安光机所,陕西,西安(710068)),曹剑中…∥光子学报。—2003,32(12),—1594-1525     

Physics design of CYCAIE-100

The design and construction of Beijing Radioactive Ion-beam Facility (BRIF) was started at China Institute of Atomic Energy -CIAE) in 2004. In this project, a 100 MeV high intensity cyclotron, CYCIAE-100, is selected as a driving accelerator for radioactive ion beam production. It will provide a proton beam of 75—100 MeV with an intensity of 200—500 μA. The scheme adopted in this design, i.e.,     

土壤中16种多环芳烃测量方法准确度的平衡均匀水平试验

采用5个浓度水平样品并通过7家实验室进行协同评定试验,验证了土壤中萘、苊、苊烯、芴、菲、蒽、荧蒽、芘、苯并(a)蒽、屈、苯并(b)荧蒽、苯并(r)荧蒽、苯并(a)芘、二苯并(a.h)蒽、苯并(g.h.i)苝、茚并(1.2.3-cd)芘等16种多环芳烃分析方法的稳定性与准确性。测量结果经一致性和离群值检查后,土壤中16种多环芳烃在5.00—1000ng/g浓度水平范围内,重复性标准差为5.78—14.8ng/g,再现性标准差为16.2—23.8ng/g,单个样品中的1-氟萘替代物质量监控指标回收率分别为72.7%—105%,检测方法准确、可靠。     

光学仪器 光学导航、制导设备

V448.2 2004053940 折反式大视场星敏感器光学系统设计=Design on a catadioptric system for star sensors with wide field of view[刊,中]/吴峰(苏州大学现代光学技术研究所,江苏,苏州(215006)),沈为民∥光学技术。—2004,30(2)。—142145     

固体激光器

TN248.1 2004031719 二极管泵浦1064nm单频Nd:YVO_4激光器的研究=Study of a diode-pumped single—frequency Nd:YVO_4 laserat 1064nm[刊,中]/郑权(中科院长春光机所.吉林,长春(130022)),赵岭∥光学技术.—2003,29(6).—675-676,679     

Label-free surface-enhanced infrared spectro-electro-chemical analysis of the Redox potential shift of cytochrome c complexed with a cardiolipin-containing lipid membrane of varied composition

In this study, a lipid membrane was fabricated by fusing cardiolipin-phosphatidylcholine(CL PC, 1:4) vesicles onto a hydrophobic surface of 1-dodecanethiol(DT) preadsorbed on a nanostructured gold film. By changing the concentration of the DT adsorption solution, we constructed a series of CL PC-DT bilayers with different hydrophobicity to study the effects of lipid membrane characteristics on the adsorption conformation of cytochrome c(Cyt c). Electrochemical analysis showed that the formal potential is 0.24 V for Cyt c-CL PC-DT(10), 0.2 V for Cyt c-CL PC-DT(20), and 0.16 V for Cyt c-CL PC-DT(40) — a gradual positive shift with the decreasing DT concentration — relative to the potential of native cyt c(0.02 V). Potential-induced surface-enhanced infrared adsorption difference spectroscopy revealed that the gradual positive shift of the formal potential of CL-bound cyt c is determined by the environment with the gradually lowered dielectric constant for the heme cofactor in CL-bound cyt c(Fe3+).     

Two-color cesium magneto-optical trap with a ladder-type atomic system

We demonstrate a magneto-optical trap(MOT) with counter-propagating two-color cooling b('ams in a cesium6S1/2 — 6P3/2 — 8S!/2(852.3 + 794.6 nm) atomic system. Based on the conventional MOT due entirely to the852.3 nm cooling laser5 s scattering forces, we replace one of the six 852.3 inn cooling beams witli a 794.6 11111 cooling beam. Our two-color MOT can efficiently cool and trap atoms from the red to blue detuning sides of two-photon resonance without pre-cooling. The technique is promising for the direct generation of correlated photon pairs in a two-color MOT based on diamond-configuration four-wave mixing.     

信息光学 其他

TP242.6 2004053603 基于光学小波变换的机器人视觉传感器设计=Design on a robot vision sensor based on optical wavelet transform[刊,中]/戴士杰(河北工业大学机器人及自动化研究所,天津(300130)),岳宏…∥光电工程。—2004,31(1)。—