scholarly journals Characterization of swelling behavior of carbon nano-filler modified polydimethylsiloxane composites

2021 ◽  
pp. 009524432110061
Author(s):  
Bo Yang ◽  
Balakrishnan Nagarajan ◽  
Pierre Mertiny
Keyword(s):  
Digital Image Analysis ◽  
Swelling Behavior ◽  
Optical Measurements ◽  
Natural Phenomenon ◽  
Cross Linking ◽  
Dimensional Changes ◽  
Experimental Findings ◽  
Carbon Based

Polymers may absorb fluids from their surroundings via the natural phenomenon of swelling. Dimensional changes due to swelling can affect the function of polymer components, such as in the case of seals, microfluidic components and electromechanical sensors. An understanding of the swelling behavior of polymers and means for controlling it can improve the design of polymer components, for example, for the previously mentioned applications. Carbon-based fillers have risen in popularity to be used for the property enhancement of resulting polymer composites. The present investigation focuses on the effects of three carbon-based nano-fillers (graphene nano-platelets, carbon black, and graphene nano-scrolls) on the dimensional changes of polydimethylsiloxane composites due to swelling when immersed in certain organic solvents. For this study, a facile and expedient methodology comprised of optical measurements in conjunction with digital image analysis was developed as the primary experimental technique to quantify swelling dimensional changes of the prepared composites. Other experimental techniques assessed polymer cross-linking densities and elastic mechanical properties of the various materials. The study revealed that the addition of certain carbon-based nano-fillers increased the overall swelling of the composites. The extent of swelling further depended on the organic solvent in which the composites were immersed in. Experimental findings are contrasted with published models for swelling prediction, and the role of filler morphology on swelling behavior is discussed.

In Vitro and In Vivo Characterization of Scleral Implant of Indomethacin: Role of Plasticizer and Cross-Linking Time

Drug Delivery ◽  
2003 ◽  
Vol 10 (4) ◽  
pp. 269-275 ◽  
Author(s):  
M. Thilek Kumar ◽  
C. Rajeswari ◽  
J. Balasubramaniam ◽  
J. K. Pandit ◽  
S. Kant
Keyword(s):  
Cross Linking ◽  
In Vivo Characterization

In Vitro and In Vivo Characterization of Scleral Implant of Indomethacin: Role of Plasticizer and Cross-Linking Time

Drug Delivery ◽  
2003 ◽  
Vol 10 (4) ◽  
pp. 269-275
Author(s):  
M. Thilek Kumar ◽  
C. Rajeswari ◽  
J. Balasubramaniam ◽  
J. K. Pandit ◽  
S. Kant
Keyword(s):  
Cross Linking ◽  
In Vivo Characterization

scholarly journals A Comparative Analysis on Organic and Inorganic Core Binders for a Gravity Diecasting Al Alloy Component

2021 ◽  
Author(s):  
A. Fortini ◽  
M. Merlin ◽  
G. Raminella
Keyword(s):  
Moisture Absorption ◽  
Time Frame ◽  
Environmental Benefits ◽  
Optical Measurements ◽  
Al Alloy ◽  
Alloy Component ◽  
Core System ◽  
Dimensional Changes ◽  
Component Design ◽  
Experimental Findings

AbstractThe last two decades have seen a growing trend toward the use of inorganic binders in core making for the metalcasting field. Despite the health and environmental benefits of the inorganic binders, wider commercial use requires ongoing technical improvements to address some potential inherent limitations of this technology. Considering that inorganic cores can suffer from storage stability, this study sets out to check whether inorganic core binders are fit to replace organic ones in producing a gravity diecasting Al alloy component. First, the humidity resistance of both organic and inorganic sand cores, within a typical time-frame storage in the foundry, was evaluated by moisture absorption tests. Then, 3D optical measurements were performed to assess the relative dimensional changes of inorganic cores. Last, the influence of the core system was analyzed through microstructural and mechanical investigations on castings manufactured by using organic and inorganic binders. The experimental findings have shown that the moisture absorption during storage in the foundry warehouse, which lasted up to 14 days, was not enough to jeopardize the functionality of the cores. Furthermore, the tensile and microstructural outcomes revealed that inorganic cores could comply with both high component design requirements and even more stringent environmental regulations of foundries.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

TEM characterization of proton-exchanged LiNbO3 optical waveguides

1986 ◽  
Vol 44 ◽  
pp. 480-481
Author(s):  
W. E. Lee
Keyword(s):  
Refractive Index ◽  
Benzoic Acid ◽  
Optical Waveguides ◽  
Total Internal Reflection ◽  
Index Of Refraction ◽  
Optical Measurements ◽  
Lithium Ions ◽  
Wide Channel ◽  
Tem Characterization

An optical waveguide consists of a several-micron wide channel with a slightly different index of refraction than the host substrate; light can be trapped in the channel by total internal reflection.Optical waveguides can be formed from single-crystal LiNbO3 using the proton exhange technique. In this technique, polished specimens are masked with polycrystal1ine chromium in such a way as to leave 3-13 μm wide channels. These are held in benzoic acid at 249°C for 5 minutes allowing protons to exchange for lithium ions within the channels causing an increase in the refractive index of the channel and creating the waveguide. Unfortunately, optical measurements often reveal a loss in waveguiding ability up to several weeks after exchange.

Platelet Accumulation on Fibrin-coated Polyethylene: Role of Platelet Activation and Factor XIII

1995 ◽  
Vol 73 (05) ◽  
pp. 850-856 ◽  
Author(s):  
F D Rubens ◽  
D W Perry ◽  
M W C Hatton ◽  
P D Bishop ◽  
M A Packham ◽  
...  
Keyword(s):  
Factor Xiii ◽  
Cross Linking ◽  
Internal Diameter ◽  
Static System ◽  
Graft Occlusion ◽  
Platelet Binding ◽  
Coated Surface ◽  
Platelet Accumulation ◽  
Polyethylene Tubing

SummaryPlatelet accumulation on small- and medium-calibre vascular grafts plays a significant role in graft occlusion. We examined platelet accumulation on the surface of fibrin-coated polyethylene tubing (internal diameter 0.17 cm) during 10 min of flow (l0ml/min) at high wall shear rate (764 s-1). Washed platelets labelled with 51Cr were resuspended in Tyrode solution containing albumin, apyrase and red blood cells (hematocrit 40%). When the thrombin that was used to form the fibrin-coated surface was inactivated with FPRCH2C1 before perfusion of the tubes with the platelet:red blood cell suspension, the accumulation of platelets was 59,840 ± 27,960 platelets per mm2, whereas accumulation on fibrin with residual active thrombin was 316,750 ± 32,560 platelets per mm2 (n = 4). When the fibrin on the surface was cross-linked by including recombinant factor XIII (rFXIII) in the fibrinogen solution used to prepare the fibrin-coated surface, platelet accumulation, after thrombin neutralization, was reduced by the cross-linking from 46,974 ± 9702 to 36,818 ± 7964 platelets per mm2 (n = 12, p <0.01). Platelet accumulation on tubes coated with D-dimer was ten times less than on tubes coated with D-domain; this finding also supports the observation that cross-linking of fibrin with the formation of γ-γ dimers reduces platelet accumulation on the fibrin-coated surface. Thrombin-activated platelets themselves were shown to cross-link fibrin when they had adhered to it during perfusion, or in a static system in which thrombin was used to form clots from FXIII-free fibrinogen in the presence of platelets. Thus, cross-linking of fibrin by FXIII in plasma or from platelets probably decreases the reactivity of the fibrin-containing thrombi to platelets by altering the lysine residue at or near the platelet-binding site of each of the γ-chains of the fibrinogen which was converted into the fibrin of these thrombi.

Tridegin, a Novel Peptidic Inhibitor of Factor XIIIa from the Leech, Haementeria ghilianii, Enhances Fibrinolysis In Vitro

1997 ◽  
Vol 77 (05) ◽  
pp. 0959-0963 ◽  
Author(s):  
Lisa Seale ◽  
Sarah Finney ◽  
Roy T Sawyer ◽  
Robert B Wallis
Keyword(s):  
Potent Inhibitor ◽  
Platelet Rich Plasma ◽  
Factor Xiiia ◽  
Cross Linking ◽  
Fibrinolytic Enzymes ◽  
Small Polypeptide ◽  
Tissue Plasminogen ◽  
Protein Cross Linking

SummaryTridegin is a potent inhibitor of factor Xllla from the leech, Haementeria ghilianii, which inhibits protein cross-linking. It modifies plasmin-mediated fibrin degradation as shown by the absence of D-dimer and approximately halves the time for fibrinolysis. Plasma clots formed in the presence of Tridegin lyse more rapidly when either streptokinase, tissue plasminogen activator or hementin is added 2 h after clot formation. The effect of Tridegin is markedly increased if clots are formed from platelet-rich plasma. Platelet-rich plasma clots are lysed much more slowly by the fibrinolytic enzymes used and if Tridegin is present, the rate of lysis returns almost to that of platelet- free clots. These studies indicate the important role of platelets in conferring resistance to commonly used fibrinolytic enzymes and suggest that protein cross-linking is an important step in this effect. Moreover they indicate that Tridegin, a small polypeptide, may have potential as an adjunct to thrombolytic therapy.

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