scholarly journals ESTIMATION OF THE REAL AREA OF AU NANOPARTICLES OVER HOPG USING ELECTROCHEMICAL TECHNIQUES

Anales AFA ◽  
2021 ◽  
Vol 32 (2) ◽  
pp. 48-54
Author(s):  
A. S. Fuentes ◽  
◽  
A. Herrera ◽  
L. Avalle ◽  
E. Santos ◽  
...  
Keyword(s):  
Au Nanoparticles ◽  
Electrochemical Techniques ◽  
Acid Solutions ◽  
Great Capacity ◽  
The Real ◽  
High Affinity ◽  
Real Area ◽  
Metallic Electrodes

The metallic electrodes show a high affinity for the electroadsorption processes of hydrogen and/or oxygen in acid solutions, so it is possible to characterize them by electrochemical techniques. In the present work the electroreduction of oxygenated species will be used to estimate the real areas of the electrodes designed with Au nanostructures in HOPG at different times of deposition. The results allow to conclude that Au nanostructures in HOPG can reach important electroactive areas. That is to say that despite their nanometric sizes they have a great capacity to experience the transfer of charge.

The Binding of Calcium Ions to Bovine Factor X by Rate Dialysis

1978 ◽  
Vol 40 (02) ◽  
pp. 350-357
Author(s):  
Robert H Yue ◽  
Menard M Gertler
Keyword(s):  
Molecular Weight ◽  
Dissociation Constant ◽  
Calcium Ions ◽  
Activation Process ◽  
Factor X ◽  
The Real ◽  
High Affinity ◽  
Binding Data ◽  
Sequential Mechanism ◽  
Bovine Factor

SummaryThe binding of Ca+2 to bovine factor X (molecular weight of 74,000) (Yue und Gertler 1977) was studied by the technique of rate dialysis and with the use of 45Ca+2. The binding data are consistent with a model of sequential mechanism. One mole of Ca+2 binds to the glycoprotein with a dissociation constant of 5.2 × 10-5 M and an additional 39 ± 4 moles of Ca+2 bind to this zymogen with a dissociation constant of 3.7 × 10-3M. The binding of the high affinity Ca+2 causes a functionally significant change in the zymogen, and (calcium) (factor X) complex is the real substrate in the activation process by the protease in Russell’s viper venom.

Analysis of the Real Area of Contact Between a Polymeric Magnetic Medium and a Rigid Surface

1984 ◽  
Vol 106 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Bharat Bhushan
Keyword(s):  
Complex Modulus ◽  
Critical Value ◽  
Computer Applications ◽  
Hard Material ◽  
Rigid Surface ◽  
Magnetic Medium ◽  
The Real ◽  
Real Area Of Contact ◽  
The Mean ◽  
Real Area

The statistical analysis of the real area of contact proposed by Greenwood and Williamson is revisited. General and simplified equations for the mean asperity real area of contact, number of contacts, total real area of contact, and mean real pressure as a function of apparent pressure for the case of elastic junctions are presented. The critical value of the mean asperity pressure at which plastic flow starts when a polymer contacts a hard material is derived. Based on this, conditions of elastic and plastic junctions for polymers are defined by a “polymer” plasticity index, Ψp which depends on the complex modulus, Poisson’s ratio, yield strength, and surface topography. Calculations show that most dynamic contacts that occur in a computer-magnetic tape are elastic, and the predictions are supported by experimental evidence. Tape wear in computer applications is small and decreases Ψp by less than 10 percent. The theory presented here can also be applied to rigid and floppy disks.

A ousadia do π ser racional

2020 ◽  
Author(s):  
Sidney Silva
Keyword(s):  
Rational Number ◽  
Pythagorean Theorem ◽  
Regular Polygons ◽  
The Real ◽  
Mathematical Question ◽  
Lower Limits ◽  
Mathematical Constant ◽  
Real Area

Pi (π) is used to represent the most known mathematical constant. By definition, π is the ratio of the circumference of a circle to its diameter. In other words, π is equal to the circumference divided by the diameter (π = c / d). Conversely, the circumference is equal to π times the diameter (c = π . d). No matter how big or small a circle is, pi will always be the same number. The first calculation of π was made by Archimedes of Syracuse (287-212 BC) who approached the area of a circle using the Pythagorean Theorem to find the areas of two regular polygons: the polygon inscribed within the circle and the polygon within which circle was circumscribed. Since the real area of the circle is between the areas of the inscribed and circumscribed polygons, the polygon areas gave the upper and lower limits to the area of the circle. Archimedes knew he had not found the exact value of π, but only an approximation within these limits. In this way, Archimedes showed that π is between 3 1/7 (223/71) and 3 10/71 (22/7). This research demonstrates that the value of π is 3.15 and can be represented by a fraction of integers, a/b, being therefore a Rational Number. It also demonstrates by means of an exercise that π = 3.15 is exact in 100% in the mathematical question.

A Relationship Between Autocorrelation Length and Adhesive Friction Behavior of Rough Surfaces

2005 ◽  
Author(s):  
Yilei Zhang ◽  
Sriram Sundararajan
Keyword(s):  
Rough Surface ◽  
Spatial Information ◽  
Roughness Parameter ◽  
Hertzian Contact ◽  
Root Mean Square Roughness ◽  
Friction Behavior ◽  
The Real ◽  
Real Area Of Contact ◽  
Autocorrelation Length ◽  
Real Area

Autocorrelation Length (ACL) is a surface roughness parameter that provides spatial information of surface topography that is not included in amplitude parameters such as Root Mean Square roughness. This paper presents a statistical relation between ACL and the real area of contact, which is used to study the adhesive friction behavior of a rough surface. The influence of ACL on profile peak distribution is studied based on Whitehouse and Archard’s classical analysis, and their results are extended to compare profiles from different surfaces. With the knowledge of peak distribution, the real area of contact of a rough surface with a flat surface can be calculated using Hertzian contact mechanics. Numerical calculation shows that real area of contact increases with decreasing of ACL under the same normal load. Since adhesive friction force is proportional to real area of contact, this suggests that the adhesive friction behavior of a surface will be inversely proportional to its ACL. Results from microscale friction experiments on polished and etched silicon surfaces are presented to verify the analysis.

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