scholarly journals Protein adlayer thickness on colloidal nanoparticle determined by Rayleigh-Gans-Debye approximation

2019 ◽  
Author(s):  
L Yuan ◽  
Z Zhai ◽  
L Chen ◽  
X Ge ◽  
D Li ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Curve Surface ◽  
Ex Situ ◽  
Colloidal Nanoparticles ◽  
New Approach ◽  
Debye Approximation ◽  
Wide Range ◽  
Measurement Results ◽  
Important Approach

ABSTRACTReference materials (RM)-assisted Rayleigh-Gans-Debye approximation (rm-RGDA) has been developed and used to in situ determine the size and thickness of the adlayer on the particles in solution. The particle size determined by rm-RGDA is quite close to that measured by electron microscopy but significantly smaller than that measured by DLS. The BSA adlayer absorbed on PS50, PS100 and SiO2 NPs is 3.3, 0.9 and 1.2 nm, respectively, and close to those observed by SEM, which is 4.6, 1.3 and 3.8 nm, respectively. The FTIR analysis results show that the BSA absorbed on larger particles or hydroxyl-abundant surface, e.g. PS100 and SiO2 NPs can lose its secondary structure, e.g. α-helix, to a great extent and that absorbed on a more curve surface, e.g. smaller PS50 particles can largely preserve its secondary structure as its free state. The measurement results show the curvature of the NPs is closely related to the structure change of the adsorbed protein. This method provide a facile and new approach to measure the size and its adlayer change of the hybrid and core-shell structured nanoparticles in a wide range of wavelength.SIGNIFICANCEQuantitative study on the adsorption of the protein on colloidal nanoparticles is an important approach to understand the biophysical effect, compared with other ex situ methods such as TEM and SEM, where the specimen are undergone pre-processing and no longer the original state in measurement. It is, therefore, a big challenge. In order to cope with this challenge, UV-vis based RGDA has been developed and applied to in situ measure the size of the dispersed colloidal nanoparticles and their protein adlayer thickness, where the protein adlayer thickness on the colloidal nanoparticles can be easily determined. We believe this method provide a facile and sensitive way to in situ measure the dimension change of hybrid colloidal nanoparticles.

scholarly journals Interfacial Adhesion and Mechanical Properties of PET Fabric/PVC Composites Enhanced by SiO2/Tributyl Citrate Hybrid Sizing

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 898
Author(s):  
Dandan Pu ◽  
Fuyao Liu ◽  
Yubing Dong ◽  
Qingqing Ni ◽  
Yaqin Fu
Keyword(s):  
Interfacial Adhesion ◽  
Ethylene Terephthalate ◽  
Sio2 Nanoparticles ◽  
New Approach ◽  
Pet Fabric ◽  
Poly Ethylene Terephthalate ◽  
Wide Range ◽  
Peeling Strength ◽  
Poly Ethylene

Poly(ethylene terephthalate) (PET) fabric-reinforced polyvinyl chloride (PVC) composites have a wide range of applications, but the interface bonding of PET fabric/PVC composites has remained a challenge. In this work, a new in-situ SiO2/tributyl citrate sizing agent was synthesized according to the principle of “similar compatibility.” The developed sizing agent was used as a PET surface modifier to enhance the interfacial performance of PET fabric/PVC composites. The morphology and structure of the PET filaments, the wettability and tensile properties of the PET fabric, the interfacial adhesion, and the tensile and tearing properties of the PET fabric/PVC composites were investigated. Experimental results showed that many SiO2 nanoparticles were scattered on the surface of the modified PET filaments. Moreover, the surface roughness of the modified PET filaments remarkably increased in comparison with that of the untreated PET filaments. The contact angle of the modified PET filaments was also smaller than that of the untreated ones. The peeling strength of the modified PET fabrics/PVC composites was 0.663 N/mm, which increased by 62.50% in comparison with the peeling strength of the untreated ones (0.408 N/mm). This work provides a new approach to the surface modification of PET and improves the properties of PET fabric/PVC composites.

In Situ Studies of the Processing of Sol-Gel Produced Amorphous Materials Using Xanes, Saxs and Curved Image Plate XRD

1999 ◽  
Vol 590 ◽  
Author(s):  
DM Pickup ◽  
G Mountjoy ◽  
RJ Newport ◽  
ME Smith ◽  
GW Wallidge ◽  
...  
Keyword(s):  
Amorphous Materials ◽  
Sol Gel ◽  
Heat Treatments ◽  
Silica Gels ◽  
Ex Situ ◽  
High Count ◽  
X Ray ◽  
Image Plate ◽  
Wide Range

ABSTRACTSol-gel produced mixed oxide materials have been extensively studied using conventional, ex situ structural techniques. Because the structure of these materials is complex and dependent on preparation conditions, there is much to be gained from in situ techniques: the high brightness of synchrotron x-ray sources makes it possible to probe atomic structure on a short timescale, and hence in situ. Here we report recent results for mixed titania- (and some zirconia-) silica gels and xerogels. Titania contents were in the range 8–18 mol%, and heat treatments up to 500°C were applied. The results have been obtained from intrinsically rapid synchrotron x-ray experiments: i) time-resolved small angle scattering, using a quadrant detector, to follow the initial stages of aggregation between the sol and the gel; ii) the use of a curved image plate detector in diffraction, which allowed the simultaneous collection of data across a wide range of scattering at high count rate, to study heat treatments; and iii) x-ray absorption spectroscopy to explore the effects of ambient moisture on transition metal sites.

In Situ Synchrotron X-ray Absorption Experiments and Modelling of the Growth Rates of Electrochemically Deposited ZnO Nanostructures

2007 ◽  
Vol 1017 ◽  
Author(s):  
Bridget Ingham ◽  
Benoit N. Illy ◽  
Jade R. Mackay ◽  
Stephen P. White ◽  
Shaun C. Hendy ◽  
...  
Keyword(s):  
Growth Rates ◽  
High Resolution Electron Microscopy ◽  
Ex Situ ◽  
X Ray ◽  
Deposition Parameters ◽  
Wide Range ◽  
Electrochemically Deposited ◽  
Electrochemical Current ◽  
X Ray Absorption

AbstractZnO is known to produce a wide variety of nanostructures that have enormous scope for optoelectronic applications. Using an aqueous electrochemical deposition technique, we are able to tightly control a wide range of deposition parameters (Zn2+ concentration, temperature, potential, time) and hence the resulting deposit morphology. By simultaneously conducting synchrotron x-ray absorption spectroscopy (XAS) experiments during the deposition, we are able to directly monitor the growth rates of the nanostructures, as well as providing direct chemical speciation of the films. In situ experiments such as these are critical to understanding the nucleation and growth of such nanostructures.Recent results from in situ XAS synchrotron experiments demonstrate the growth rates as a function of potential and Zn2+ concentration. These are compared with the electrochemical current density recorded during the deposition, and the final morphology revealed through ex situ high resolution electron microscopy. The results are indicative of two distinct growth regimes, and simultaneous changes in the morphology are observed.These experiments are complemented by modelling the growth of the rods in the transport-limited case, using the Nernst-Planck equations in 2 dimensions, to yield the growth rate of the volume, length, and radius as a function of time.

In situ Mössbauer Study of the Passive Layer Formed on the Iron Anode in Alkaline Electrolyte

1999 ◽  
Vol 64 (12) ◽  
pp. 2044-2060 ◽  
Author(s):  
Karel Bouzek ◽  
Martin Nejezchleba
Keyword(s):  
Mössbauer Spectra ◽  
Sodium Hydroxide Solution ◽  
Passive Layer ◽  
Iron Electrode ◽  
Ex Situ ◽  
Anode Surface ◽  
Alkaline Electrolyte ◽  
Mossbauer Spectra ◽  
Wide Range

In situ Mössbauer spectra of the iron electrode at anodic potential were measured in sodium hydroxide solution over a wide range of concentrations (0.1 - 14 mol l-1). It was found that the in situ Mössbauer spectra exhibit generally one sextet and one doublet corresponding to the oxide layer on the anode surface. Parameters of these spectra show only minor variations within the electrolyte concentration range of 0.1 - 7 M NaOH. A pronounced change in the spectra was observed in 14 M NaOH. The major processes taking place in the anode surface layer are based on the break-down of protective properties of the passive layer, incipient intense metal dissolution and subsequent oxidation. Important differences were also found between in situ and ex situ spectra measurements.

In-situ AFM study of the crystallization and pH-dependent stability of ZnO(0001)-Zn surfaces

2007 ◽  
Vol 1035 ◽  
Author(s):  
Markus Valtiner ◽  
Guido Grundmeier
Keyword(s):  
Electrolyte Solutions ◽  
Ex Situ ◽  
Chemical Cleaning ◽  
Single Crystalline ◽  
Afm Imaging ◽  
Wide Range ◽  
Wet Chemical ◽  
Ph Dependent ◽  
Crystalline Surfaces

AbstractPolar ZnO(0001)-Zn surfaces can be prepared as very well defined and single crystalline surfaces by hydroxide stabilization simply by introducing hydroxides via a wet chemical cleaning step. Within this proceeding we present an in-situ AFM imaging of the crystallization process. The pH dependent stability of the resulting hydroxide-stabilized surfaces was further investigated by means of an ex-situ LEED approach. These investigations show, that it is possible to obtain high quality single crystalline ZnO(0001)-Zn surfaces in a simple way. Moreover, these surfaces turned out to be very stable within a wide range of pH values between 11 and 3 of NaClO4 based 1mM electrolyte solutions.

Ex situ and In situ TEM study of the relaxation of thin films by the modified frank-read mechanism

1992 ◽  
Vol 50 (2) ◽  
pp. 1342-1343
Author(s):  
F.K. LeGoues
Keyword(s):  
Thin Films ◽  
Strain Relaxation ◽  
Lattice Parameter ◽  
Buffer Layers ◽  
Ex Situ ◽  
In Situ Tem ◽  
Wide Range ◽  
Strong Resemblance ◽  
Image Position

In recent papers, we have described a novel mechanism for strain relaxation of thin films. Because of its strong resemblance to the well known Frank-Read sources of dislocations, it was called the “Modified-Frank-Read” (MFR) mechanism. This process was first observed during the growth of compositionally graded SiGe/Si(001) thin films, where it results in dislocations pile-ups being injected deep into an initially perfect substrate, leaving the topmost part of the film relaxed and nominally defect free. This last observation opens the door to a wide range of electronic applications since it makes it possible to grow electronic grade buffer layers of arbitrary composition and lattice parameter.The exact mechanism of the reproduction of dislocations was identified through tilting experiment and analysis of several compositionally graded SiGe/Si(001) structures. These also provided the important parameters controlling this mode of strain relaxation. We thus demonstrated that the MFR mechanism corresponds to the multiplication of “corner dislocations” (dislocations whose line forms a 90° angle) by simultaneous glide on two (111) planes.

New approach in the monitoring and characterization of titanium nitride thin films

1999 ◽  
Vol 14 (2) ◽  
pp. 436-441 ◽  
Author(s):  
S. Logothetidis ◽  
E. I. Meletis ◽  
G. Kourouklis
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Ex Situ ◽  
New Approach ◽  
X Ray ◽  
Plasma Energy

In situ and ex situ spectroscopic ellipsometry (SE), Raman spectroscopy (RS), x-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) have been used to study the stoichiometry and characterize TiNx thin films deposited by magnetron sputtering at various stoichiometries. In situ SE can provide parameters, such as the plasma energy, that can be utilized for monitoring of the film stoichiometry. Besides plasma energy, optical phonon position in RS was also found to be a sensitive probe of TiNx stoichiometry as detected by RS, XPS, and ex situ SE. Under these conditions, AES faces difficulties for reliable film characterization, and the complementary use of other techniques is required for determining the exact film stoichiometry.

scholarly journals In- and ex situ PXRD studies of ZnO nanoparticle growth in sub-critical water

2014 ◽  
Vol 70 (a1) ◽  
pp. C1413-C1413
Author(s):  
Espen Bøjesen ◽  
Kirsten Jensen ◽  
Christoffer Tyrsted ◽  
Nina Lock ◽  
Mogens Christensen ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Zno Nanoparticles ◽  
Aqueous Media ◽  
Ex Situ ◽  
Synthesis Methods ◽  
Zno Nanoparticle ◽  
Characterization Methods ◽  
Wide Range ◽  
In Situ Experiments

Zinc oxide (ZnO) is a material of great scientific and industrial relevance and is used widely in a variety of applications. Synthesis of ZnO nanoparticles can be performed by a wide range of methods resulting in a tremendous variety of sizes and shapes. Different in situ characterization methods have been used to investigate the ZnO formation under various synthesis conditions; these include numerous spectroscopic methods and small angle scattering. Common for these studies is that the primary focus has been to extract information on particle size and shape of ZnO, while a more rigorous microstructural and structural analysis has been lacking. Furthermore, the aforementioned studies have primarily been focused on soft chemical synthesis methods, at low temperatures and in non-aqueous media, thus omitting the widely used environmentally benign and versatile hydrothermal method. In the present work the formation of ZnO during hydrothermal synthesis has been followed using in situ powder X-ray diffraction (PXRD) combined with Rietveld refinement, thus enabling the extraction of crystallographic as well as microstructural information during the formation and growth of ZnO. Supporting ex situ syntheses and characterization by electron microcopy, high resolution PXRD and other techniques have been used to corroborate the findings from the in situ experiments. Mapping out a vast parameter space has led to a deeper understanding of the intricate mechanisms governing the nucleation and growth of ZnO nanoparticles during hydrothermal synthesis. Among the parameters studied were the influence of temperature, type of base used and the influence of different ionic salts as synthesis directing agents. The various synthesis parameters were found to influence the following structural and microstructural features: crystallite shape, morphology and size as well as the twin-fault concentration, degree of doping and crystallinity.

scholarly journals Laser-heating system for high-pressure X-ray diffraction at the Extreme Conditions beamline I15 at Diamond Light Source

2018 ◽  
Vol 25 (6) ◽  
pp. 1860-1868 ◽  
Author(s):  
Simone Anzellini ◽  
Annette K. Kleppe ◽  
Dominik Daisenberger ◽  
Michael T. Wharmby ◽  
Ruggero Giampaoli ◽  
...  
Keyword(s):  
Light Source ◽  
Laser Heating ◽  
Theoretical Data ◽  
Heating System ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Diamond Anvil

In this article, the specification and application of the new double-sided YAG laser-heating system built on beamline I15 at Diamond Light Source are presented. This system, combined with diamond anvil cell and X-ray diffraction techniques, allows in situ and ex situ characterization of material properties at extremes of pressure and temperature. In order to demonstrate the reliability and stability of this experimental setup over a wide range of pressure and temperature, a case study was performed and the phase diagram of lead was investigated up to 80 GPa and 3300 K. The obtained results agree with previously published experimental and theoretical data, underlining the quality and reliability of the installed setup.

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