共查询到20条相似文献,搜索用时 234 毫秒
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利用低相干光纤动态光散射法测量浓悬浮液中多分散颗粒粒径分布 总被引:1,自引:0,他引:1
本文针对高浓度散射介质,用低相干光纤动态光散射技术测量浓悬浮液中多分散颗粒系的粒径及其粒径分布。利用迭代CONTIN算法对实验数据进行反演运算,得到多分散颗粒系的粒径分布结果。结果表明,浓悬浮液中多分散颗粒系的峰值粒径测量值与给定的两种标准粒径值相吻合,其误差在4%之内,粒径分布曲线中各散射颗粒所反映的散射体光强分布与根据Mie散射计算得到的理论值相吻合。实验结果证明低相干光纤动态光散射实验系统能准确测量浓悬浮液中多分散颗粒粒径及粒径分布。 相似文献
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多模光纤式动态光散射实验研究 总被引:1,自引:1,他引:0
介绍了多模光纤在动态光散射中的应用,搭建了基于多模光纤的动态光散射实验系统,并用该系统测量了单分散、多分散以及不同浓度的标准聚苯乙烯乳胶球悬浮液.结果表明,该系统可准确地测量浓度达4.5%的聚苯乙烯乳胶球溶液中悬浮颗粒的粒径分布. 相似文献
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应用动态光散射、透射电镜和粘度-剪切模型3种方法互相配合,研究了果胶与乳清分离蛋白的混合体系在热力学不相容条件下的微观结构。在90℃及pH7.4条件下,向5%蛋白浓度的乳清蛋白溶液中加入带有负电的果胶分子,可导致热变性乳清蛋白分子之间发生损耗聚集,并引发混合体系内的相分离现象。确切地说,当果胶与乳清蛋白的混合重量比小于0.08时,溶液内可观察到粒径小于300nm的聚集颗粒,体系呈现牛顿流体特征;而当混合重量比大于0.08时,体系粘度上升,切稀特征逐渐明显,聚集集团粒径接近700nm。 相似文献
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基于偏振门的动态光散射颗粒测量法的研究 总被引:1,自引:1,他引:0
为了解决动态光散射纳米颗粒测量技术无法测量高浓度颗粒粒径的难题,提出了一种基于偏振门的动态光散射测量法。从动态光散射和Mie理论出发,理论分析了在高浓度溶液下多重散射效应对散射光偏振态和颗粒粒度测量结果的影响。根据散射光偏振特点,结合偏振门检测技术,改进了传统的动态光散射光学系统。实验研究了在低浓度和高浓度溶液时,不同偏振角度下的散射光强和粒度测量值,完善了散射光的偏振理论。采用90°偏振门检偏,通过各种浓度下的实验,证明了方法的可行性。该方法较之目前同类方法具有原理和结构简单,系统易于维护的特点。 相似文献
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在pH7.0的Na2HPO4-NaH2PO4缓冲溶液中,纳米金与适配体(aptamer)结合形成较稳定的aptamer-Au复合物,且不被NaCl聚集。在85℃水浴中,K+与aptamer作用后折叠形成稳定的G-四分体结构复合物且释放出纳米金。在高浓度盐作用下,纳米金聚集成较大粒径的纳米金颗粒,导致体系563nm处的共振散射强度增大,其平均粒径为120nm。文章研究了K+ -随机单链DNA1(ssDNA1)-纳米金、K+ -ssD-NA2-纳米金和K+ -aptamer-纳米金体系的共振散射光谱特性,并用圆二色光谱技术证明了核酸适配体结构的变化。考察了pH、NaCl浓度、aptamer浓度、纳米金用量以及Cu2+、Mg2+、Pb2+、Ca2+、Al3+、Zn2+Fe3+等常见重金属离子等对测定K+的影响,结果显示这些离子不干扰测定,该法具有较好的选择性。在选定条件下,K+浓度在0.67~3350μmol·L-1范围与共振散射峰值ΔI呈良好的线性关系,回归方程、相关系数、检出限分别为ΔI=0.167c-0.7,0.9932,0.3μmol·L-1 K+。该法用于血清样品分析,结果与离子选择电极法一致。 相似文献
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动态光散射技术是一种测量纳米颗粒粒径分布的最有效方法。为了克服高浓度样品溶液中存在的多重散射效应, 本文基于单模光纤搭建了一套DLS实验系统, 传输光纤的输出端与接收光纤的接收端都作了抛光磨平处理。在模拟复杂工业环境下, 分别用低浓度单分散、不同浓度单分散以及高浓度多分散性标准聚苯乙烯乳胶球悬浮液检测了该系统的适用性。实验结果表明, 利用该系统可快速准确的测量体积分数达40%的聚苯乙烯乳胶球悬浮液中的纳米颗粒粒径及其分布。 相似文献
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本文利用动态光散射技术研究丙酮酸脱氢酶,得到其微观结构方面的若干信息.测量出其PDC结构及E_2-X-K结构的半径;发现在较低浓度下,聚集现象可以忽略,尺寸分布是单分散性分布,动态光散射谱的线宽Γ与散射波矢q分别呈Γ∝q~2及Γ∝q~3关系.而在较高浓度下,Γ∝qα,α为分数,这时尺寸分布里多分散性分布. 相似文献
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The appearance of spherical particles resulting from phase separation in dilute solutions of poly(N-isopropylacrylamide) has been observed by dynamic light scattering (DLS). The particles have a relatively narrow size distribution. The size of particles increases with increasing concentration of polymer, and decreasing heating speed. Electron microscopy confirms the existence of spherical particles with size and polydispersity in agreement with DLS. 相似文献
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The size, surface charge and agglomeration state of nanoparticles under physiological conditions are fundamental parameters
to be determined prior to their application in toxicological studies. Although silica-based materials are among the most promising
candidates for biomedical applications, more systematic studies concerning the characterisation before performing toxicological
studies are necessary. This interest is based on the necessity to elucidate the mechanisms affecting its toxicity. We present
here TEM, SAXS and SMPS as a combination of methods allowing an accurate determination of single nanoparticle sizes. For the
commercial material, Ludox TM50 single particle sizes around 30 nm were found in solution. DLS measurements of single particles
are rather affected by polydispersity and particles concentration but this technique is useful to monitor their agglomeration
state. Here, the influence of nanoparticle concentration, ionic strength (IS), pH and bath sonication on the agglomeration
behaviour of silica particles in solution has been systematically investigated. Moreover, the colloidal stability of silica
particles in the presence of BSA has been investigated showing a correlation between silica and protein concentrations and
the formation of agglomerates. Finally, the colloidal stability of silica particles in standard cell culture medium has been
tested, concluding the necessity of surface modification in order to preserve silica as primary particles in the presence
of serum. The results presented here have major implications on toxicity investigations because silica agglomeration will
change the probability and uptake mechanisms and thereby may affect toxicity. 相似文献
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基于碱性胱氨酸水溶液在恒温水浴条件下可形成荧光性分子聚集体的特性,发展一种荧光光谱直接检测胱氨酸含量的新方法。实验结果表明,将pH 9.0的0.01 mol·L-1的胱氨酸溶液,于90 ℃恒温水浴热处理12 h后,胱氨酸分子可形成大小为12.5nm粒径的荧光分子聚集纳米团簇(FANC)结构,并发射蓝绿色荧光。采用荧光光谱(FL)、透射扫描电镜(TEM)和质谱(MS)对FANC的荧光性能和结构进行表征,并初步探讨光致发光机理。FANC在410 nm最佳激发波长条件下,于508 nm处具有最佳的荧光发射信号,体系的平均荧光寿命为6.028 ns,荧光量子产率为8.48%。FANC在水溶液中具有稳定的光漂白性、酸碱稳定性和光谱不依赖性质,粒子的Zeta电位为-57 mV,结合150 nm的水合粒径结果,表明形成的团簇表面亲水且带负电荷。质谱结果显示体系中存在多种胱氨酸分子间脱水形成的分子碎片,因此推测FANC是胱氨酸分子在水溶液环境中因分子间作用力形成分子聚集体。基于FANC的荧光强度和原料胱氨酸的浓度在1.0×10-5~6.0×10-4 mol·L-1范围内呈良好的线性关系,可将该方法用于胱氨酸片中含量的测定,结果与中国药典中记载的滴定比色法相吻合。相比于其他检测方法,该方法具有操作简便,检测限低,精确度高等优点。 相似文献
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Phosphorylcholine (PC)-functionalized poly(amido amine) (PAMAM) dendrimers were prepared and used as both reducing and stabilizing
agents for synthesis of highly stable and reactive gold nanoparticles (Au NPs). Biomimetic PC-functionalized PAMAM dendrimers-stabilized
gold nanoparticles (Au DSNPs) were formed by simply mixing the PC modified amine-terminated fifth-generation PAMAM dendrimers
(G5-PC) with AuCl4
− ions by controlling the pH, no additional reducing agents or other stabilizers were needed. The obtained Au DSNPs were shown
to be spherical, with particle diameters ranging from 5 to 12 nm, the sizes and growth kinetics of Au DSNPs could be tuned
by changing the pH and the initial molar ratio of dendrimers to gold as indicated by transmission electron microscopy (TEM)
and UV–Vis data. The prepared Au DSNPs showed excellent stability including: (1) stable at wide pH (7–13) values; (2) stable
at high salt concentrations up to 2 M NaCl; (3) non-specific protein adsorption resistance. More importantly, surface functionalization
could be performed by introducing desired functional groups onto the remained reactive amine groups. This was exemplified
by the glucose conjugation. The glucose conjugated Au DSNPs showed bio-specific interaction with Concanavalin A (Con A), which
induced aggregation of the Au NPs. Colorimetric detection of Con A based on the plasmon resonance of the glucose conjugated
Au DSNPs was realized. A limit of detection (LOD) for Con A was 0.6 μM, based on a signal-to-noise ratio (S/N) of 3. These
findings demonstrated that the PC modified Au DSNPs could potentially serve as a versatile nano-platform for the biomedical
applications. 相似文献
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Yamanaka M Inaka K Furubayashi N Matsushima M Takahashi S Tanaka H Sano S Sato M Kobayashi T Tanaka T 《Journal of synchrotron radiation》2011,18(1):84-87
Although polyethylene glycol (PEG) is the most widely used precipitant in protein crystallization, the concentration of co-existing salt in the solution has not been well discussed. To determine the optimum salt concentration range, several kinds of protein were crystallized in a 30% PEG 4000 solution at various NaCl concentrations with various pH levels. It was found that, if crystallization occurred, the lowest effective salt concentration depended on the pH of the protein solution and the pI of the protein molecule; that is, higher salt concentrations were required for crystal growth if the difference between pH and pI was increasing. The linear relationship between the charge density of the protein and the ionic strength of the crystallization solution was further verified. These results suggested that the lowest effective concentration of salt in a crystallization solution can be predicted before performing a crystallization experiment. Our results can be a tip for tuning crystallization conditions by the vapor-diffusion method. 相似文献
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Hautbergue GM Golovanov AP 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,191(2):335-339
Decrease in experimental sensitivity of cryoprobe experiments for salty samples, attributed to increased sample conductivity, has been a long-standing issue in protein NMR. Salt concentration can not be simply reduced as this often leads to protein aggregation. A simple and inexpensive solution to this problem is demonstrated here. We show that even for proteins prone to aggregation, the traditional solubilizing salt, 100mM NaCl, can be completely replaced by 50mM l-Arg and l-Glu. This replacement simultaneously reduces the sample conductivity and improves protein solubility. Up to a 6-fold overall increase in experimental sensitivity was achieved, in comparison with the traditional salty buffer. At constant protein concentration up to 2-fold increase in sensitivity was observed. The lengths of the proton pi/2 pulses were also significantly decreased, up to the level typical for non-salty samples in water. 相似文献
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《Journal of Electrostatics》2014,72(1):22-27
Silk sericin has been recently investigated for many biological roles. This study aimed to develop the new delivery system to control the release of silk sericin. The alginate microparticles encapsulating silk sericin were fabricated by electrospraying technique. Concentrations of silk sericin and alginate polyelectrolyte solutions were investigated. All microparticles had an average size of 264–284 μm and could entrap silk sericin with high entrapment efficiency (84–89%). The microparticles could deliver silk sericin in a rate-controlled manner. This study would show a promising controlled release application of silk sericin protein from alginate microparticles fabricated by the means of electrostatic forces. 相似文献
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Chécot F Lecommandoux S Klok HA Gnanou Y 《The European physical journal. E, Soft matter》2003,10(1):25-35
This paper discusses the self-assembly of block copolymers into vesicular morphology. After a brief state of art of the field,
a system based on an amphiphilic poly(butadiene)-b-poly(-L-glutamic acid) (PB-b-PGA) diblock copolymer in aqueous solution is discussed in detail. The aggregation behavior of this block copolymer has been
investigated by means of fluorescence spectroscopy, dynamic (DLS) and static (SLS) light scattering as well as transmission
electron microscopy (TEM). The diblock copolymer was found to form well-defined vesicles in water. The size of these so-called
polymersomes or peptosomes could be reversibly manipulated as a function of both pH and ion strength. Depending on the pH
of the aqueous solution, the hydrodynamic radii of these vesicles were found to vary from 100 nm to 150 nm. By cross-linking
the 1,2-vinyl double bonds present in the polybutadiene block, the ability to transform a transient supramolecular self-organized
aggregate into a permanent “shape-persistent stimuli-responsive nanoparticle” has been demonstrated.
Received 25 June 2002 and Received in final form 22 October 2002 Published online: 11 March 2003 相似文献
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Particulate gels are known to be formed by bovine β-lactoglobulin near the isoelectric point when partial unfolding is allowed
to occur under heating. The aggregation process of the protein has been investigated within the context of a nucleation and
growth process by preparing gels under precisely controlled thermal histories. This was achieved using a Differential Scanning
Calorimeter (DSC) to provide controlled heating rates, and known final temperatures and incubation times. The resulting particulate
gels were characterized by their particle size and polydispersity using Environmental Scanning Electron Microscopy (ESEM),
which permits hydrated samples to be observed. Particle size was found to decrease with increasing final temperature, with
the aggregation taking longer to reach completion for lower temperatures. Particle size was also found to decrease with increasing
heating rate. This system could be modelled as evolving via nucleation and growth by taking into account the fact that the
concentration of the aggregating species was varying as a function of temperature as well as time. The intrinsic tryptophan
fluorescence as a function of temperature was used as a guide to the fraction of unfolded protein in solution, thereby permitting
successful comparisons between the model predictions and the particle sizes to be made.-1 相似文献
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Silk fibroin, which is derived from sericin through degumming, is mainly used as a biomaterial. However, interest in functional verification and industrial applications of sericin has been growing for several years. We used ultrasonication to simplify the extraction process of the silk peptide under low salt conditions at 20 °C, instead of using the conventional conditions of high salt and temperature. The concentration of the silk peptide was measured to determine the optimized extraction time and solvent, which were 4 h and 0.1 N NaOH, respectively. The molecular weight of the enzyme-treated silk peptide was measured using SDS-PAGE and GPC. Silk peptide treated with papain after ultrasound had a molecular weight of less than 5 kDa, and the papain treated-silk peptide reduced solar ultraviolet-induced COX-2 expression through inhibition of ERK phosphorylation. This is the first study investigating simultaneous extraction of fibroin and sericin, which can be used for mass production of food materials. 相似文献