乙二胺N,N-二(6-氨基青霉烷酸)二乙酸与金属离子的相互作用

通过荧光光谱法研究了乙二胺N,N-二(6-氨基青霉烷酸)二乙酸(L1)与10种金属离子的相互作用.结果表明:Co2+、Mg2+、Ca2+和Mn2+的加入对L1的荧光发射没有明显影响；K+、Fe3+、Gd3+、Ni2+和Zn2+的加入对L1的荧光发射有微弱的猝灭作用;Cu2+对L1的荧光发射有明显的猝灭作用;当Cu2+浓度为L1的200倍时,猝灭率达到68.73％;计算得出Cu2+对L1的Stern-Volmer猝灭常数Kav为106400L·tmol-1.     

ZnO@SiO_2核壳量子点的制备及其荧光性能的研究

用一种操作简单、反应条件温和的方法制备了分散性好的超微小Zn O@Si O2核壳量子点透明溶液,利用透射电子显微镜(TEM)、紫外吸收光谱(UV)、荧光光谱(FL)、纳米粒度和ZETA电位分析仪等技术对所制备纳米粒子的粒径大小、吸收光谱、发光性质进行表征。结果表明,Zn O@Si O2核壳量子点平均粒径在3~5 nm,在紫外灯下发出黄绿色荧光,紫外最大吸收在330 nm左右,可以发射出510 nm的荧光。同时,系统地考察了p H值、温度、不同金属阳离子以及不同阴离子对量子点荧光强度的影响。实验结果表明:当p H≤7时,量子点荧光完全猝灭;当p H7时,量子点荧光强度随着p H值的增加而增强,当p H为9.0时,荧光强度达到最大,然后随着p H值的升高荧光略有降低。量子点随着温度的升高荧光强度逐渐降低,当温度达到50℃以上荧光完全猝灭。一价金属离子对量子点荧光强度基本没有影响,二价金属离子对量子点荧光削弱程度的大小顺序为Fe2+Mn2+Cu2+Pb2+Co2+Ba2+Mg2+,三价金属离子对量子点荧光削弱程度的大小顺序为Fe3+Cr3+Bi3+Al3+。其中,Fe3+、Fe2+、Bi3+、Cr3+、Mn2+等金属离子对量子点的荧光有猝灭作用,PO43-、HPO42-、H2PO4-等离子对量子点荧光稍有增加作用,HCO3-、CO32-、CH3COO-、SO32-等阴离子对量子点的荧光有削弱甚至猝灭的作用,Cl-、SO42-、NO3-等离子对量子点荧光几乎没有影响。     

光谱学研究重金属离子参与下对甲萘威与ctDNA相互作用的影响

应用紫外、荧光光谱分析方法,研究了离体条件八种重金属参与下对农药甲萘威与小牛胸腺DNA的相互作用的影响。当有不同重金属离子参与时,甲萘威的猝灭常数及其结合位点数都发生了不同的变化。通过计算和分析,重金属离子对甲萘威与ct-DNA的加合物的影响程度为Pb2+>Ag+>Cu2+>Ni2+>Co2+>Zn2+>Cd2+>Cr3+。通过400 mol·L－1的不同金属离子对ctDNA的作用研究,得出不同离子对DNA的双螺旋结构的破坏能力强弱依次为：Pb2+>Cd2+>Ag+>Co2+>Zn2+≈Cu2+>Ni2+>Cr2+。两种光谱所得结果表明不同重金属离子对DNA的作用机理不同。     

富勒醇与血清白蛋白相互作用的光谱学研究

采用荧光光谱法和紫外-可见吸收光谱法研究了不同温度下富勒醇与血清白蛋白的相互作用机理,研究结果表明,富勒醇对人和牛血清白蛋白的内源荧光有明显的猝灭作用, 猝灭过程均为静态猝灭,并测定和计算得到不同温度下富勒醇与血清白蛋白反应的结合常数(K_HSA273 K1.546×104,K_HSA293 K1.513×104;K_BSA273 K13.920×104,K_BSA293 K939.500×104)、结合位点数(n_HSA293 K0.952 2;n_BSA293 K1.376 2)。通过结合反应的热力学数据分析,推测出富勒醇与血清白蛋白之间主要靠疏水作用结合;富勒醇与BSA结合强度明显大于富勒醇与HSA的结合强度,BSA的结合常数受温度影响更大;人和牛血清白蛋白在273和293 K的结合位点数在0.901→1.376之间,BSA与富勒醇结合位点数略大于HAS。同时采用分子模拟对接方法,预测富勒醇对牛血清白蛋白的结合部位和作用方式;通过AlignX序列分析法得到BSA与HSA的氨基酸序列相似度较高,在序列160和185附近氨基酸序列差异性较大,推测这是影响两种蛋白质之间与富勒醇作用方式的关键位点。     

同步与三维荧光光谱法研究日落黄和人血清蛋白的相互作用

日落黄是一种具有潜在危害性的人工合成色素。选用人血清蛋白为研究对象,利用荧光光谱法分析了日落黄对人血清蛋白荧光的猝灭作用,确定了荧光猝灭反应的猝灭常数Ksv,结果表明日落黄对人血清蛋白的荧光猝灭作用类型为静态猝灭。运用同步荧光光谱法分析日落黄与人血清蛋白结合表明：日落黄与人血清蛋白的结合靠近色氨酸附近,引发色氨酸残基趋向伸展状态,人血清蛋白的结构发生改变。此外,在模拟人体生理条件下选用10种不同的金属离子加入到日落黄和人血清蛋白的反应体系中,运用三维荧光法检测金属离子对体系的影响,结果表明Cu2+,Pb2+,Ni2+和Mn2+对猝灭过程有着促进作用,其中Ni2+的影响最大,增幅达 22.6 %;而Fe2+和Zn2+对猝灭过程有着抑制作用,抑制率达14.12%和14.2%。本研究的实验方法适用于研究食品添加剂的毒性,有助于保护食品安全,维护人体健康。     

两种药物与金属离子的作用

研究了磺胺间甲氧嘧啶、诺氟沙星与Ce3+,La3+,Tb3+,Co2+,Fe3+作用体系的荧光和紫外特性。结果表明,La3+和Tb3+对磺胺间甲氧嘧啶的荧光起增敏作用,而Fe3+,Co2+,Ce3+使磺胺间甲氧嘧啶的荧光猝灭;Ce3+,La3+,Tb3+,Co2+,Fe3+对诺氟沙星的荧光均起猝灭作用。紫外的测定结果与荧光基本相同。     

金属离子修饰的ZnS/PAMAM纳米复合材料的荧光性能研究

用荧光分光光度法研究了Zn2+,Mn2+,Cd2+,Na+,K+,Ag+,Cu2+和Pb2+等金属离子修饰的ZnS/PAMAM树形分子纳米复合材料的荧光发射性能。结果表明：不同金属离子修饰效果不同。Zn2+,Mn2+和Cd2+修饰后,ZnS/PAMAM树形分子纳米复合材料的荧光发射强度有不同程度提高;Ag+,Cu2+和Pb2+的修饰对荧光有不同程度的猝灭作用;而Na+和K+的修饰对荧光发射无明显影响。与修饰前相比,Cd2+离子修饰的ZnS/PAMAM树形分子纳米复合材料标记的潜指纹发射的蓝色荧光更加明亮,与背景反差更加明显。这对提高潜指纹的显现精度和准确率有很好的借鉴价值。     

荧光法研究Pb2+与牛血清白蛋白的相互作用

在模拟生理条件下, 用荧光光谱法研究了Pb2+与牛血清白蛋白(BSA)的相互作用. 结果表明 BSA分子中色氨酸和酪氨酸残基具有荧光发射性质, 以283 nm激发BSA, 在341 nm处有很强的荧光发射. 在加入Pb2+ 后, 发现Pb2+-BSA强荧光峰的位置不变, 但荧光强度随着Pb2+浓度的增大而明显减弱, 说明Pb2+对BSA有荧光猝灭现象, 猝灭以静态猝灭为主, 由Stern-Volmer方程求得Pb2+表观猝灭常数Kq=9.5×1012 L·mol-1·s-1. Pb2+主要与BSA中的N配位形成21配合物, 表观络合常数lgK=11.61.     

铅离子对碳纳米颗粒荧光发射规律的影响

以热解石墨为原料,利用电化学方法,制备了荧光碳纳米颗粒。系统地研究了在不同浓度、时间、pH值、温度等条件下,Pb2+离子对碳纳米颗粒荧光发射规律的影响。实验结果表明:Pb2+离子不改变光谱形状,但可以降低荧光峰值强度;Pb2+离子作用荧光碳纳米颗粒的时间越长,猝灭效率越低;pH值不同,猝灭效率不同;随着温度的升高,Pb2+离子对碳纳米颗粒荧光的猝灭效率逐步提高。其猝灭机理可能为电荷转移猝灭和动态猝灭。     

Pb2+对鱼肠DNA光谱特性的影响

利用紫外吸收光谱、荧光光谱、电泳手段研究了不同浓度Pb2+与鱼肠DNA的相互作用. 紫外吸收光谱测试表明 随着Pb2+的加入, DNA产生明显的减色效应, 同时DNA的207 nm峰发生明显蓝移; 荧光发射光谱结果表明, 随着Pb2+的加入, DNA荧光发射强度逐渐降低, Pb2+在DNA上的结合位点数为0.8个, Pb2+引起DNA的荧光猝灭属于静态猝灭, 结合位点的结合常数分别为6.08×104和2.82×104 L·mol-1; 电泳结果表明, 不同浓度的外源Pb2+处理未引起DNA的断裂. 认为外源Pb2+ 对DNA的构象有一定的破坏作用, 但并不引起DNA的断裂.     

Ionization Energies in Dithiocarbamate Derivatives of α-Amino Acids: A Spectroscopic Investigation on the Effect of the Side Chain

Ionization energies of dithiocarbamate derivatives of α-amino acids (glycine, alanine, valine, leucine) have been determined by X-Ray Photoelectron Spectroscopy. The values determined increase as the side chain in these amino acids becomes longer, a fact probably related to the different donor ability of these radicals. A parallel effect has been also observed in the precise positions of the IR absorption bands for these compounds.     

氯化钠团簇的形成规律与结合能计算

当离子蒸气冷凝形成团簇时，其结构表现出特定的规律。文中对不同大小不同形状的氯化钠团簇结构与结合能进行了计算，以求揭示离子蒸气冷凝形成团簇的一些规律，并与实验结果进行对照。     

The effect of nonparabolicity on binding energy of ground and excited states in a corrugated quantum well

The binding energy of a hydrogenic impurity is calculated in a Ga_1−xAl_xAs/Ga_1−yAl_yAs corrugated quantum well within the single band effective mass approximation for different Al concentration. Binding energy of the ground state and the excited state of a donor is calculated, with the inclusion of 2D Hartree dielectric screening function. The effect of nonparabolicity of the conduction band is considered through the energy dependent effective mass. The effect of nonparabolicity on spin–orbit interaction energy is found. The oscillator strength coupling between the ground state and the excited state is calculated. The dependence of the donor binding energy on the well width and the Al-concentration is discussed. These results are discussed with the available data in the literature.     

Binding energies of negatively charged excitons in quantum disks

The Hamiltonian of a negatively charged exciton X⁻ (trion) in a quantum disk with parabolic confinement has been diagonalized to obtain the binding eigenenergy values of the L1 states as a function of the electron-to-hole effective mass ratio and the disk radius. It is found that a negatively charged exciton X⁻ in a quantum disk may have the second bound state with orbital angular momentum L=1 and the triplet state of the two bound electrons.     

Li and Na Co-decorated carbon nitride nanotubes as promising new hydrogen storage media

The capacity of Li and Na co-decorated carbon nitride nanotube (CNNT) for hydrogen storage is studied using first-principles density functional theory. The results show that with two H₂ molecules attached to per Li and four H₂ molecules per Na the Li and Na co-decorated CNNT gains a gravimetric density of H₂ as high as 9.09 wt% via electrostatic interaction without the clustering of the deposited metal atoms (at T=0 K). The average adsorption energy of hydrogen molecule is in the range of 0.09-0.22 eV/H₂, which is suitable for practical hydrogen storage at ambient temperatures.     

Pu和Au原子4f5/2和4f7/2的结合能计算

基于Koopmans定理,应用MCDF方法计算了Pu和Au原子4f5/2和4f 7/2的结合能以及PuO2所引起的化学位移,一般大于固体的相应值.     

Constraints on two-neutron separation energy in the Borromean C nucleus

The recently extracted matter radius of carbon isotope ²²C allows us to estimate the mean-square distance of a halo neutron with respect to the center-of-mass of this nucleus. By considering this information, we suggest an energy region for an experimental investigation of the unbound ²¹C virtual state. Our analysis, in a renormalized zero-ranged three-body model, also indicates that the two-neutron separation energy in ²²C is expected to be found below ∼0.4 MeV$\sim 0.4\text{MeV}$, where the ²²C is approximated by a Borromean configuration with a pointlike ²⁰C and two s-wave halo neutrons. A virtual-state energy of ²¹C close to zero, would make the ²²C, within Borromean nuclei configurations, the most promising candidate to present an excited bound Efimov state or a continuum three-body resonance.     

The binding energy of hydrogen-like impurity in quantum dots with convex bottom in magnetic field

Within the framework of effective mass approximation and variational method, the electronic and impurity states in spherical quantum dots with convex bottom in magnetic field are calculated. Calculations are carried out both for on-center and off-center impurities. The impurity binding energy dependencies on radius, measure of convexity of quantum dot bottom, impurity position and magnetic field induction are obtained for the Ga_1-xAl_xAs/Ga_1-yAl_yAs system.     

Effect of the dielectric-constant mismatch and magnetic field on the binding energy of hydrogenic impurities in a spherical quantum dot

Within the effective mass approximation and variational method the effect of dielectric constant mismatch between the size-quantized semiconductor sphere, coating and surrounding environment on impurity binding energy in both the absence and presence of a magnetic field is considered. The dependences of the binding energy of a hydrogenic on-center impurity on the sphere and coating radii, alloy concentration, dielectric-constant mismatch, and magnetic field intensity are found for the GaAs–Ga_1−xAl_xAs–AlAs (or vacuum) system.     

Fluorometric investigation of the interaction between nitrophenols and 7-hydroxy-4-azidomethylcoumarin

The interaction between nitrophenols and 7-hydroxy-4-azidomethylcoumarin has been investigated by fluorescence and UV-vis absorbance spectroscopy. Quenching mechanisms have been evaluated by fluorescence measurements at different temperatures. Stern-Volmer quenching constant K_sv and corresponding thermodynamic parameters ΔH⁰, ΔG⁰ and ΔS⁰ were calculated. Binding studies concerning the number of binding sites ‘n’ and apparent binding constant ‘K’ were performed by fluorescence quenching method.