高F值南极磷虾小分子肽的制备优化及其对HepG2细胞影响研究

该实验以脱脂南极磷虾粉为原料,首先通过单因素(料液比、加酶量、温度、时间)和正交试验优化双酶酶解工艺条件,并采用超滤、活性炭脱芳手段制备南极磷虾高F值小分子肽(Antarctic krill peptides with high-Fischer ratio,HF-AKP),然后采用CCK-8法观察HF-AKP对人肝癌细胞株HepG2生长情况的影响,最后,通过流式细胞计数和ELISA方法分别检测HepG2细胞周期分布和细胞凋亡相关蛋白表达情况。结果显示,碱性蛋白酶的最佳酶解条件为料液比1∶17.5(g∶mL),加酶量5.0%(质量分数),温度55℃,酶解6 h;复合风味蛋白酶的最佳酶解条件为加酶量4.0%,酶解3 h。经双酶酶解的脱脂南极磷虾酶解液的水解度为(17.4±0.2)%,得到F值为2.4±0.2的小分子肽(Antarctic krill peptides,AKP,<5 kDa),再经活性炭脱芳处理得到F值为87.2±0.7的HF-AKP。HF-AKP对体外培养的人肝癌细胞株HepG2的细胞生长具有抑制作用,且呈剂量、时间正向依赖性;此外,HF-AKP可使HepG2细胞生长阻滞于G0/G1期;其凋亡机制可能与Bax/Bcl-2蛋白表达比值增加,以及人核因子κB(nuclear factorκB,NF-κB)蛋白表达减少有关,推测HF-AKP可能有一定抗肿瘤功效。

基于自然语言处理的蛋白质小分子亲和力值预测

蛋白质与小分子的相互作用研究对药物的研发非常重要,而现有的蛋白质小分子亲和力值的预测方法存在成本高、精度低等问题.为此提出了一种新的蛋白质小分子亲和力值的预测方法,利用自然语言处理技术对蛋白质结构数据与小分子指纹数据进行处理,并利用梯度提升决策树模型进行预测.实验表明,该方法的精度较原有方案有较大提高.

关于微分中值定理的几何推广

通过曲线段自身的几何性质研究了微分中值定理的几何表示 ,把中值定理的几何意义推广到空间曲线段 ,并由此推理得几个常见的中值定理形式及其推广形式。

pH值敏感相分离特性的蛋白质酶解试剂研究

通过DEC/NHS偶联反应将胰蛋白酶(Trypsin)连接到具有pH值敏感性的壳聚糖(CS)链上。Trypsin-CS偶联物保留了CS的pH值敏感相分离特性及Trypsin的酶催化活性。浊度滴定实验表明,此偶联物的临界相分离pH值(CPSP)仍保持在偏中性范围内,并且随CS的分子量降低而略有上升。这种偏中性的CPSP值有利于相分离循环过程中保持酶的催化活性。分子量为8×104的CS与Trypsin的偶联物在存放30d后可保留69%的初始酶活性。偶联物经过6次循环使用后的残余活性为初始活性的79%。Trypsin-CS偶联物可在低于CPSP值的条件下对蛋白质进行均相酶解,并在高于CPSP值时从催化体系中分离出来。HPLC肽谱分析表明,Trypsin-CS偶联物中Trypsin的自降解被显著抑制,因而有效消除了Trypsin自降解肽段对肽谱分析的干扰。

聚丙烯酰胺的合成与研究

采用过硫酸钾—氮三丙酰胺引发体系 ,进行丙烯酰胺水溶液聚合。考察了溶液PH值 ,温度等工艺条件对产物分子量 ,转化率及聚合物溶解性能的影响。在PH=8,60℃时,氨水滴加7滴时,可得到分子量为62.00E4聚丙烯酰胺及转化率为98.94 %。

两级膜超滤纯化右旋糖酐的工艺研究

以右旋糖酐40粗品(Dex-40)为研究对象,选择不同截留分子量(molecular weight cut-off,MWCO)的两级超滤膜对其进行纯化并研究膜分离工艺条件。通过高效液相凝胶色谱(HPGPC)跟踪检测各级产物的相关指标,筛选合适膜组件并研究原料液浓度、操作压力、浓缩倍数和水洗次数对膜分离效果的影响规律。结果Dex-40溶液经过两级膜超滤处理后,均一性明显提高,D值由2.79降低到1.17,纯度达99.99%,重均分子量(Mw)52317,得率42.8%,为两级膜超滤纯化特定分子量右旋糖酐的工艺提供数据基础。

Method for obtaining high-resolution velocity spectrum based on weighted similarity

Seismic wave velocity is one of the most important processing parameters of seismic data,which also determines the accuracy of imaging.The conventional method of velocity analysis involves scanning through a series of equal intervals of velocity,producing the velocity spectrum by superposing energy or similarity coefficients.In this method,however,the sensitivity of the semblance spectrum to change of velocity is weak,so the resolution is poor.In this paper,to solve the above deficiencies of conventional velocity analysis,a method for obtaining a high-resolution velocity spectrum based on weighted similarity is proposed.By introducing two weighting functions,the resolution of the similarity spectrum in time and velocity is improved.Numerical examples and real seismic data indicate that the proposed method provides a velocity spectrum with higher resolution than conventional methods and can separate cross reflectors which are aliased in conventional semblance spectrums;at the same time,the method shows good noise-resistibility.

Orbital-Free Density Functional Theory for Molecular Structure Calculations

We give here an overview of the orbital-flee density functional theory that is used for modeling atoms and molecules. We review typical approximations to the kinetic energy, exchange-correlation corrections to the kinetic and Hartree energies, and constructions of the pseudopotentials. We discuss numerical discretizations for the orbital-free methods and include several numerical results for illustrations.

K-means Find Density Peaks in Molecular Conformation Clustering

Performing cluster analysis on molecular conformation is an important way to find the representative conformation in the molecular dynamics trajectories.Usually,it is a critical step for interpreting complex conformational changes or interaction mechanisms.As one of the density-based clustering algorithms,find density peaks(FDP)is an accurate and reasonable candidate for the molecular conformation clustering.However,facing the rapidly increasing simulation length due to the increase in computing power,the low computing efficiency of FDP limits its application potential.Here we propose a marginal extension to FDP named K-means find density peaks(KFDP)to solve the mass source consuming problem.In KFDP,the points are initially clustered by a high efficiency clustering algorithm,such as K-means.Cluster centers are defined as typical points with a weight which represents the cluster size.Then,the weighted typical points are clustered again by FDP,and then are refined as core,boundary,and redefined halo points.In this way,KFDP has comparable accuracy as FDP but its computational complexity is reduced from O(n^(2))to O(n).We apply and test our KFDP method to the trajectory data of multiple small proteins in terms of torsion angle,secondary structure or contact map.The comparing results with K-means and density-based spatial clustering of applications with noise show the validation of the proposed KFDP.

Joint Optimal Sensing Threshold and Subcarrier Power Allocation in Wideband Cognitive Radio for Minimising Interference to Primary User

Cognitive Radio （CR） can use the fre- quency band allocated to a Primary User （PU） on the premise that it will prevent significant of avoiding causing great interference to the PU. In this paper, we consider a wideband CR system where the Secondary User （SU） mini- raises its interference to the PU by jointly al- locating the optimal sensing threshold and sub- carrier power. A multi-parameter optimization problem is formulated to obtain the joint opt- imal allocation by alternating direction opti- mization, which minimises the total interfer- ence to the PU over all of the subcarriers sub- ject to the constraints on the throughput, Bit Error Rate （BER） and maximal total power of the SU, the subcarrier rate and interference power of the PU, and the false alarm and mis- detection probabilities of each subcarrier. The simulation results show that the proposed joint allocation algorithm can achieve the desired mitigation on the interference to the PU at the different subcarrier gains.

Adsorption of Phenol Aqueous Solutions and Two Nitroderivated on Activated Carbon

The adsorption of phenol, p-nitrophenol and 2,4-dinitrophenol in aqueous phase on activated carbon is performed by evaluating factors such as the pH of the solution, it is found that the value in adsorbate molecule is upper and lower of its respective pKa. Likewise, the heterogeneity of the adsorbent solid is evaluated using commercial activated carbon, which is modified by means of oxidation with HNO3 and reduction with H2 fluxing at high temperature, treatments represent variatians in textural properties of solid which changed equally the superficial chemistry of the same. The major concentration of retained plLenol compound in some samples of carbon is produced in pH values which the solute is basically molecular.

CALCULATING ACCURATE PERIODIC MOTIONS OF HARMONICALLY FORCED PIECEWISE LINEAR OSCILLATORS

This paper presents an efficient numerical scheme for calculating the periodic motion of a harmonically forced piecewise linear oscillator very accurately. The scheme is based on the shooting technique with the traditional numerical Poincare mapping and its Jacobian replaced by the piecewise analytic ones. Thus, the scheme gets rid of the requirement of the current schemes for an assumed order of the oscillator trajectory passing through different linear regions. The numerical examples in the paper demonstrate that the new scheme, compared with the current schemes, enables one to cope with more complicated dynamics of harmonically forced piecewise linear oscillators.

First-principles Study of Electron Transport Through Oligoacenes

The electronic transport properties of oligoacenes sandwiched between two Au（111） surfaces with serial and parrallel configurations were investigeted by using a fully self-consistent nonequilibrium Green＇s function method combined with density functional calculations. This theoretical results show that the conductivity of oligoacenes with both sandwiched configurations at low bias voltage is mainly determined by the tail of the transmission peak from the perturbed highest occupied molecular orbital. When the molecular length increases, the zero-bias voltage conductance G（0） of oligoacenes with serial configuration neither follows Magoga＇s exponential law nor displays the even-odd oscillation effect, while the G（O） of the oligoacenes sandwiched with parallel configuration monotonically increases. The reduction of energy gaps, the alignment of the Fermi level, and the spatial distribution of the perturbed molecular orbitals are used to self-consistently explore the transport mechanism through oligoacenes.

Statistical Average of Spin Operators for Calculation of Three-Component Magnetization （II）： Solution of Equation

In this paper, the solution of Chebyshev equation with its argument being greater than 1 is obtained. The initial value of the derivative of the solution is the expression of magnetization, which is valid for any spin quantum number S. The Chebyshev equation is transformed from an ordinary differential equation obtained when we dealt with Heisenberg model, in order to calculate all three components of magnetization, by many-body Green＇s function under random phase approximation. The Chebyshev functions with argument being greater than 1 are discussed. This paper shows that the Chebyshev polynomials with their argument being greater than 1 have their physical application.

Numerical analysis of surface plasmons excited on a thin metal grating

The authors numerically investigated the characteristics of surface plasmons excited on a thin metal grating placed in planer or conical mounting. After formulating the problem, the solution method, Yasuura＇s method （a modal expansion approach with least-squares boundary matching） was described. Although the grating is periodic in one direction, coupling between TE and TM waves Occurs because arbitrary incidence is assumed. This requires the employment of both TE and TM vector modal functions in the analysis. Numerical computations showed： （l） the excitation of surface plasmons with total or partial absorption of incident light; （2） the resonance character of the coefficient of an evanescent order that couples the plasmon surface wave; （3） the field profile and Poynting＇s vector. The plasmons excited on the surfaces of a thin metal grating are classified into three types： SISP, SRSP, and LRSP, different from each other in the feature of field profile and energy flow. In addition, the eigenvalue of a plasmon mode was obtained by solving a sequence of diffraction problems with complex-valued angles of incidence and using the quasi-Newton algorithm to predict the real angle of incidence at which the absorption occurs.

Numerical analysis of interaction between solute atom and extended dislocation using force multipoles

The interaction between a solute atom and an extended dislocation was investigated using a continuum approximation method with force multipoles.The dislocation core structure of extended dislocation was modeled with the Peierls-Nabarro model discretized with a number of infinitesimal Volterra dislocations.The interaction energy and force between a nickel solute atom and perfect and extended dislocation in copper were successfully calculated using the force multipoles.The results clearly show that the core structure of extended dislocation weakens the interaction with solute atoms.The interaction energy and force for extended dislocations are almost the half of those for perfect dislocations.

Decomposition of Soliton Hierarchy Associated with a Schrodinger Type Spectral Problem

The soliton hierarchy associated with a Schrodinger type spectral problem with four potentials is decomposed into a class of new finite-dimensional Hamiltonian systems by using the nonlinearized approach. It is worth to point that the solutions for the soliton hierarchy are reduced to solving the compatible Hamiltonian systems of ordinary differential equations.

Ground roll separation method via threshold fi ltering and constraint of seismic wavelet support in curvelet domain

Most traditional ground roll separation methods utilize only the difference in geometric characteristics between the ground roll and the refl ection wave to separate them.When the geometric characteristics of data are complex,these methods often lead to damage of the reflection wave or incompletely suppress the ground roll.To solve this problem,we proposed a novel ground roll separation method via threshold filtering and constraint of seismic wavelet support in the curvelet domain;this method is called the TFWS method.First,curvelet threshold fi ltering(CTF)is performed by using the diff erence of the curvelet coeffi cient of the refl ection wave and the ground roll in the location,scale,and slope of their events to eliminate most of the ground roll.Second,the degree of the local damaged signal or the local residual noise is estimated as the local weighting coeffi cient.Under the constraints of seismic wavelet and local weighting coeffi cient,the L1 norm of the refl ection coeffi cient is minimized in the curvelet domain to recover the damaged refl ection wave and attenuate the residual noise.The local weighting coeffi cient in this paper is obtained by calculating the local correlation coeffi cient between the high-pass fi ltering result and the CFT result.We applied the TFWS method to simulate and fi eld data and compared its performance with that of frequency and wavenumber filtering and the CFT method.Results show that the TFWS method can attenuate not only linear ground roll,aliased ground roll,and nonlinear noise but also strong noise with a slope close to the refl ection events.

On Estimation of Fully Entangled Fraction

We study the fully entangled fraction （FEF） of arbitrary mixed states. New upper bounds of FEF are derived. These upper bounds make complements on the estimation of the value of FEF. For weakly mixed quantum states, an upper bound is shown to be very tight to the exact value of FEF.

On Common Eigenvector of Parametric Interaction Hamiltonian and Number-Difference Operator Derived by Virtue of Entangled State Representation

By virtue of the properties of bipartite entangled state representation we derive the common eigenvector of the parametric Hamiltonian and the two-mode number-difference operator. This eigenvector is superposition of some definite two-mode Foek states with the coefficients being proportional to hypergeometric functions. The Gauss contiguous relation of hypergeometrie functions is used to confirm the formal solution.