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1.
国产硅藻土吸附尿激酶机理的研究   总被引:4,自引:0,他引:4  
在常温下, 尿激酶在浙江土和吉林土表面的吸附等温线分别为V型和II型; 焙烧后两者皆转为III型。吸附等温线类型与硅藻土表面结构、孔结构、表面ζ电位有关。在400℃焙烧的硅藻土等电点值最低, 吸附量最大; 改性后, 吸附量也发生改变。本文还测定了尿激酶在硅藻土表面的吸附形态, 其吸附等温线方程符合0/(1-0)=(Kc)^1/β, 并讨论了平衡常数K和尿激酶吸附功能链段数β随温度的变化。  相似文献   

2.
DFT calculations have been performed to explore the aminotriazine adsorption on graphene surfaces.Relative energies,equilibrium geometries and electronic structures of monomer and dimer of aminotriazine molecules adsorbed at the surface were investigated and analyzed in details.It was found that the hydrogen atoms in the NH2 group of aminotriazine molecules are directed toward the graphene surface,and the adsorption energy increases as the NH2 group is added.The adsorbed aminotriazine molecules facilely form a dimer through the hydrogen bonding interactions,and the two aromatic rings of optimized structure of 2-amino-1,3,5-triazine(B) dimmer(denoted by B2) and melamine(D) dimmer(denoted by D2) are parallel to the graphene sheet.The large deviation of the averaged adsorption energy of B2 and D2 compared to monor adsorption may reflect the increase of π-π repulsion and the effect of hydrogen bond formation.The electronic structure analyses reveal that the formation of hydrogen bonds in melamine dimer has great influence on the adsorption mode at the graphene surface.  相似文献   

3.
4.
The influence of the uppermost substrate layer on the structural properties of sputtered lithium cobalt oxide (LiCoO2) is discussed in this work. For this purpose, bare, oxidized, and platinum-coated silicon wafers, as well as stainless steel and titanium sheets, were used as substrates. The resulting crystal structure of LiCoO2 deposited on these substrates was analyzed and discussed. The LiCoO2 thin films were deposited by RF magnetron sputtering with different film thicknesses. A subsequent annealing step at 700 °C was performed to induce the crystallinity of LiCoO2. The crystal orientation was determined by X-ray diffraction. The obtained results show a strong dependency of LiCoO2's crystal structure on the surface the film is deposited on. However, the strong influence of the film thickness reported in previous publications could not be observed. If LiCoO2 is deposited on the substrates with a metallic surface, a strong (003) preferential orientation is obtained for a wide range of film thicknesses. In contrast, sputtering of LiCoO2 on bare and on oxidized silicon wafers results in a (101) dominated crystal structure for the different film thicknesses. These experiments show the importance of the characterization of LiCoO2's crystal structure in the intended battery setup.  相似文献   

5.
The basic results on the effect of temperature on the equilibrium and thermodynamic characteristics of ion-exchange systems and the use of this effect in developing reagentless methods for ion-exchange separation are considered.  相似文献   

6.
本文合成了4种螺噁嗪类化合物,并通过FTIR、1H NMR、ESI-MS对其结构进行了表征。研究了吲哚环上氮原子和噁嗪环9′位不同的取代基及溶剂化效应对其光致变色性能的影响。结果表明,吲哚环的氮原子引入体积较大的基团对螺噁嗪最大吸收波长无明显影响,然而有利于开环体的稳定性,且溴原子的引入会影响螺噁嗪的光响应性;噁嗪环9′位上的供电子基团会降低螺噁嗪的开环体稳定性;螺噁嗪开环体的褪色过程符合一级动力学方程;在非质子溶剂中,螺噁嗪开环体的最大吸收波长呈现正向溶剂化效应;有机酸的加入,可以增加开环体的热稳定性。  相似文献   

7.
微量稀土加入铝或铝合金中,如果加入方法、数量、时间得当,可明显改善材料的多项性能.稀土对铝及铝合金的影响规律和作用机理,已取得了一些进展,但对稀土铝合金的热力学性质,尤其是溶解态稀土的研究少有报导[‘,2].本工作采用L即.95C。。。。FZ。。多晶作为固体电解  相似文献   

8.
The present work aimed at describing the spectral behaviour of the serotonin and to evaluate its acidity constants using three different methods, using two spectrophotometry titrations and a third method that involved point-by-point analysis, which permitted to monitor closely and determine the evolution of the serotonin species in solution as a function of time. The three methods allowed estimation of three acidity constants associated to the same number of functional groups that form part of the molecule. The results given by the point-by-point analysis were: log(beta1) = 24.95 +/- 0.12; log(beta2) = 20.20 +/- 0.10; log(beta3) = 10.89 +/- 0.018.  相似文献   

9.
软段结构对聚氨酯性能影响的研究   总被引:3,自引:0,他引:3  
用熔融缩聚法俣成了己二酸系和己二酸/芳香二酸混合系两个系列的聚酯;同溶液一步法将部分聚酯与MDI反应,形成一系列聚酯型氨酯,以化学分析,VPO,IR,DSC,WAXD,力学拉伸等手段对聚酯和聚氨酯进行了表征;讨论了软段聚酯的结构对聚氨酯的结晶性,耐热性,粘结性等性能的影响。  相似文献   

10.
第三相界面对高分子共混物粗化过程的影响研究   总被引:8,自引:3,他引:5  
共混物相分离的机理已有研究[1].但对共混物分散相的粗化过程的研究则不多见.1977年,Cahn等[2]预言第三相界面与低分子共混物之间存在的浸润作用对相分离过程应有较大影响.近年Tanaka等[3]的研究结果表明,在几何空间受限的条件下,含有小分子...  相似文献   

11.
To study the structural characteristics and physical properties of droplets sitting on the inclined substrates and cylindrical surfaces, wetting experiments are conducted in different cases. The profile curves of the droplets are recorded and extracted by a CCD camera and image processing, respectively. Contact angles are figured out by fitting the profile curves and taking the derivative at the front and rear triple points. Based on the experimental results, a Surface Evolver is employed to simulate the morphological changes by minimizing the total energy of the system. Furthermore, theoretical shapes and feature parameters, including the heights and the spreading distances of the droplets, which are hard to obtain by normal experimental measurements are provided. The contact-angle hysteresis when the heavy droplet sitting on the inclined substrate is discussed. Meanwhile, the evolutions of the contour of the three-phase contact line are predicted when heavy droplets spread on the convex and concave cylindrical surfaces, respectively. This study provides a finite-element analysis method to describe the surface properties of molten droplets on different substrates, and the simulation results agree well with the experimental results.  相似文献   

12.
金属离子修饰的M41S介孔分子筛催化剂体系是当前多相催化剂研究的热点.虽然有关介孔分子筛金属离子修饰的方法有多种[1],但均存在着负载的金属粒子在载体表面负载量低或分散不均匀等缺点;采用本课题组的有机官能团化法[2]可以得到高分散度和高负载量的介孔分子筛负载金属氧化物  相似文献   

13.
The chemical shifts of carboxyl proton in benzoic acid have been measured in a variety of solvents. The characteristic monomer and dimer chemical shifts have been evaluated at 23°. A detailed discussion is given to illustrate the solvent shifts of carboxyl proton, from which the dielectric constant of solvent is considered as the main factor. The plot of carboxyl proton shift against (∈—1)/(∈+1) reveals a roughly linear dependence, indicating that a high field shift will be brought about by an increasing dielectric constant of solvent. Another linear relationship between log (δ—δD) and log ∈ suggests that an increase of ∈ will destroy the cyclic dimer, leading to an increase of the monomeric population and therefore to a higher field of the carboxyl proton signal.  相似文献   

14.
The effect of the nature of the dopant on the response of a sensor array based on films of polyaniline (PAn) under the influence of the vapor of various organic solvents was studied. It was established that the main factors determining the magnitude of the response of PAn films are the morphology of the films and the accepting power of the analyte molecules (in the case of "standard" acid dopants) and also the possibility of additional donor–acceptor interaction between the analyte molecules and the dopant (in the case of heteropoly acid dopants). It was shown that with heteropoly acids as dopants of PAn it is possible to increase substantially the selectivity of the response of the sensor array.  相似文献   

15.
Depending on the substituent on the phosphorus(III) atom, reactions of tris(dialkylamino)phosphines, 2-diethylamino-1,3,2-benzodioxaphosphole, and benzene-1,4-diylbis(N,N,N′,N′-tetraethylphosphonous diamide) with 1-alkylisatins lead to the formation of isoindigo derivatives, spirophosphoranes, or spirooxiranes whose structure was determined by NMR spectroscopy and X-ray analysis.  相似文献   

16.
A general approach to understanding the complex nature of the friction of friction-resistant heatresistant thermoplastics has been developed. This approach made it possible to idenify two main factors determining the basic character of the friction of these polymers on steel: the dispersion component of the intermolecular interaction energy and the molecular weight. Specific properties of some polymers can be used to refine the friction behavior.  相似文献   

17.
Propolis or bee-glue is the third important product of honey bees after honey and wax. Known for thousands of years for its curative effects it is finding evermore attention in alternative and classical therapy in recent times against, e.g. infections, inflammations, dermatologic diseases and in wound healing.

Microcalorimetric experiments were performed on the influence of several propolis samples from Germany, Uruguay, Ethiopia and of a commercial propolis tincture on growth and metabolism of the recommended gram-positive bacterium Micrococcus luteus. Propolis extracts were prepared following established recipies for the water-soluble and insoluble components and the precipitate.

Addition of these extracts to a growing M. luteus culture in different growth phases resulted in a strong decline of the heat production rate, a prolongation of the lag phase or an introduction of a new, second lag phase, while the form of the calorimetric power-time curve remained unchanged. The calorimetric response showed a linear dependence on the propolis concentration. Although the quantitative gain of the extracts from the different propolis samples was nearly constant, the effects varied considerably between the specimens used.

The calorimetric investigations were supplemented by polarographic oxygen monitoring and by the standard agar well technique to determine the growth inhibition factor of the propolis extracts.  相似文献   


18.
Ceiling temperatures (Tc) and reactivities of N-phenylmethacrylamide (PMAm) and o-substituted PMAm's in free-radical polymerization and the thermal stability of the polymers obtained were investigated. Although PMAm and o-substituted analogs gave the same Tc, 123°C at 0.64 mol/L in N,N-dimethylformamide, that of 2,6-dimethyl-PMAm was found to be as low as 65°C. These findings are interpreted in terms of steric hindrance as a consequence of the bulkiness of the 2- and 6-substituents and of the rigid and planar structure expected for the polymers. In copolymerization with styrene, the o-monosubstituted PMAm's were estimated to be more reactive than PMAm by a factor of about 3 except for o-phenyl-PMAm. The enhanced reactivity of the PMAm with a relatively small o-substituent is explained by ground-state strain of the monomer tending toward a planar structure. 2,6-Dimethyl-PMAm and o-phenyl-PMAm showed lower and slightly higher reactivities than PMAm, respectively, probably due to the blocking effect of these substituents against the approaching polymer radical. Enhancement of thermal degradation owing to the substitution was confirmed by means of thermogravimetric analyses of the polymers. The polymers from the 2,6-dimethyl-substituted and the o-monosubstituted PMAm' exhibited similar maximum-degradation-rate temperatures.  相似文献   

19.
以羟基磷灰石和氧化镁为晶粒生长抑制剂制备的纳米氧化钛陶瓷为研究对象, 采用体外成骨细胞Ros17/28与材料复合培养的方法, 通过MTT法、荧光染色法和SEM细胞形貌观察等手段综合判断细胞在材料表面的活性, 以此评价纳米氧化钛陶瓷的生物活性. 结果表明, 以羟基磷灰石为晶粒生长抑制剂的氧化钛陶瓷晶体颗粒尺寸达到纳米级, 其生物活性超出了以氧化镁为晶粒生长抑制剂的氧化钛陶瓷和纯羟基磷灰石陶瓷, 具有优异的生物相容性, 是生物活性陶瓷.  相似文献   

20.
为探讨富硒米的剂量对大鼠免疫功能的影响和富硒米用于保健食疗提供有意义的实验依据,选用纯种SD大鼠40只,随机分为高中低三个剂量组,分别给予富硒米和常规饲料喂养30d,称重,取血做T淋巴细胞转化和自然杀伤细胞活性试验。结果表明:①富硒米能显著提高大鼠T淋巴细胞转化率,中剂量组与对照组比较有显著性差异(t检验,P〈0.05)。②富硒米大鼠NK活性对照比较,没有显著性差异 。结论是富硒米能显著提高大鼠T  相似文献   

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