Thermodynamics of ß-cyclodextrine/water Interactions

1997 ◽  
Vol 52 (4) ◽  
pp. 348-350 ◽  
Author(s):  
C. Margheritis ◽  
A. Marini ◽  
C. Sinistri
Keyword(s):  
Single Parameter ◽  
Experimental Results ◽  
Semiempirical Calculations ◽  
Hydration Process ◽  
Compensation Mechanism ◽  
Entropy Increase ◽  
Substrate Stabilization

Abstract From a purely enthalpic standpoint, the ß-CD hydration, as studied by semiempirical calculations, appears improbable, in contrast to experiment. For the spontaneous hydration process, a compensation mechanism, connected with substrate stabilization and/or entropy increase, is suggested on the basis of simple thermodynamic considerations. The analysis is done on the basis of a single parameter Ew (> 0), which represents the energy needed to transfer a mole of water from the liquid to the ß-CD absorbed phase.The model, although simple, allows predictions largely consistent with the experimental results, while suggesting possible interpretations.

Thresholding Selection Based on Fuzzy Entropy and Bee Colony Algorithm for Image Segmentation

2013 ◽  
pp. 165-183
Author(s):  
Yonghao Xiao ◽  
Weiyu Yu ◽  
Jing Tian
Keyword(s):  
Image Segmentation ◽  
Fuzzy Entropy ◽  
Single Parameter ◽  
Entropy Function ◽  
Experimental Results ◽  
Superior Performance ◽  
Image Thresholding ◽  
Minimum Function ◽  
Minimum Value ◽  
Bee Colony

Image thresholding segmentation based on Bee Colony Algorithm (BCA) and fuzzy entropy is presented in this chapter. The fuzzy entropy function is simplified with single parameter. The BCA is applied to search the minimum value of the fuzzy entropy function. According to the minimum function value, the optimal image threshold is obtained. Experimental results are provided to demonstrate the superior performance of the proposed approach.

Two Different Theoretical Approaches to the Base Pressure Problem in Two-Dimensional Supersonic Flow

1978 ◽  
Vol 29 (2) ◽  
pp. 114-130 ◽  
Author(s):  
M. Tanner
Keyword(s):  
Supersonic Flow ◽  
Flow Model ◽  
The Body ◽  
Experimental Results ◽  
Base Pressure ◽  
Two Dimensional ◽  
Reattachment Point ◽  
Fundamental Idea ◽  
Entropy Increase ◽  
Theoretical Approaches

SummaryThe basic physical idea underlying the theories based on the flow model of CHAPMAN and KORST is that the base pressure can be predicted if the pressure at the reattachment point is known. In the new theory of TANNER the fundamental idea is the connection between the drag of the body and the entropy increase in the flow. This paper presents the essence of both theories together with theoretical and experimental results.

scholarly journals An Entropy-Based Failure Prediction Model for the Creep and Fatigue of Metallic Materials

Entropy ◽  
2019 ◽  
Vol 21 (11) ◽  
pp. 1104 ◽  
Author(s):  
Jundong Wang ◽  
Yao Yao
Keyword(s):  
Prediction Model ◽  
Damage Mechanics ◽  
Failure Time ◽  
Failure Prediction ◽  
Damage Parameter ◽  
Experimental Results ◽  
Creep Process ◽  
Creep Failure ◽  
Entropy Increase ◽  
Increase Rate

It is well accepted that the second law of thermodynamics describes an irreversible process, which can be reflected by the entropy increase. Irreversible creep and fatigue damage can also be represented by a gradually increasing damage parameter. In the current study, an entropy-based failure prediction model for creep and fatigue is proposed based on the Boltzmann probabilistic entropy theory and continuum damage mechanics. A new method to determine the entropy increment rate for creep and fatigue processes is proposed. The relationship between entropy increase rate during creep process and normalized creep failure time is developed and compared with the experimental results. An empirical formula is proposed to describe the evolution law of entropy increase rate and normalized creep time. An entropy-based model is developed to predict the change of creep strain during the damage process. Experimental results of metals and alloys with different stresses and at different temperatures are adopted to verify the proposed model. It shows that the theoretical predictions agree well with experimental data.

scholarly journals Study on the Influence of Nanosilica Sol on the Hydration Process of Different Kinds of Cement and Mortar Properties

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3653
Author(s):  
Haibao Liu ◽  
Qiuyi Li ◽  
Dunlei Su ◽  
Gongbing Yue ◽  
Liang Wang
Keyword(s):  
Compressive Strength ◽  
Cement Mortar ◽  
Setting Time ◽  
Economic Value ◽  
Experimental Results ◽  
Hydration Process ◽  
Hydration Reaction ◽  
X Ray Diffraction ◽  
Gaseous State ◽  
Promotion Effect

Compared with nanosilica collected in a gaseous state, nanosilica sol has great economic value and application significance for improving the performance of concrete and mortar. In this study, the influence of nanosilica sol on the hydration process of different kinds of cement is studied by means of hydration heat analysis,X-ray diffraction analysis(XRD)and other methods, and the properties of mortar such as setting time, mechanical properties and porosity are also studied to characterize the influence of nanosilica sol on the macroscopic properties of mortar. The experimental results show that nanosilica sol can accelerate the hydration rate of two kinds of cement and promote the hydration reaction degree of cement, and this promotion effect increases with the increase in nanosilica sol content. At the same time, nanosilica sol can significantly shorten the setting time of the two kinds of cement, and it is more obvious with the increase in content. Excessive content of nanosilica sol will adversely affect the permeability resistance of mortar. It may be caused by the weak interval formed by nanosilica particle clusters in the mortar matrix, which can be supported by the mortar pore structure distribution test. At the same time, the influence of nanosilica sol on the hydration of the two kinds of cement is different, and the compressive strength of HBSAC cement mortar increases first and then decreases after adding nanosilica sol; However, the compressive strength of P·O 42.5 cement mortar increases gradually after adding nanometer silica sol. This shows that nanosilica sol does not effectively promote the hydration of β-C2S in high belite sulfoaluminate cement (HBSAC) mortar. Based on the above experimental results, it can be concluded that when the content of nanosilica sol is about 1%, it has the best promotion effect on the hydration of the two kinds of cement and the performance of mortar.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

Observation of Phase Contrast Images in STEM and CTEM Modes by Using 100 kV Field Emission Electron Gun

1974 ◽  
Vol 32 ◽  
pp. 390-391
Author(s):  
Y. Harada ◽  
T. Goto ◽  
H. Koike ◽  
T. Someya
Keyword(s):  
Field Emission ◽  
Phase Contrast ◽  
Image Formation ◽  
Fresnel Diffraction ◽  
Experimental Results ◽  
Electron Gun ◽  
Scanning Microscopy ◽  
Emission Electron ◽  
Lattice Images

Since phase contrasts of STEM images, that is, Fresnel diffraction fringes or lattice images, manifest themselves in field emission scanning microscopy, the mechanism for image formation in the STEM mode has been investigated and compared with that in CTEM mode, resulting in the theory of reciprocity. It reveals that contrast in STEM images exhibits the same properties as contrast in CTEM images. However, it appears that the validity of the reciprocity theory, especially on the details of phase contrast, has not yet been fully proven by the experiments. In this work, we shall investigate the phase contrast images obtained in both the STEM and CTEM modes of a field emission microscope (100kV), and evaluate the validity of the reciprocity theory by comparing the experimental results.

A new dissociation mode for dislocations in silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 346-347
Author(s):  
A. Ourmazd ◽  
G.R. Booker ◽  
C.J. Humphreys
Keyword(s):  
Detailed Examination ◽  
Experimental Results ◽  
Dislocation Network ◽  
Weak Beam ◽  
Phosphorus Doped

A (111) phosphorus-doped Si specimen, thinned to give a TEM foil of thickness ∼ 150nm, contained a dislocation network lying on the (111) plane. The dislocation lines were along the three <211> directions and their total Burgers vectors,ḇt, were of the type , each dislocation being of edge character. TEM examination under proper weak-beam conditions seemed initially to show the standard contrast behaviour for such dislocations, indicating some dislocation segments were undissociated (contrast A), while other segments were dissociated to give two Shockley partials separated by approximately 6nm (contrast B) . A more detailed examination, however, revealed that some segments exhibited a third and anomalous contrast behaviour (contrast C), interpreted here as being due to a new dissociation not previously reported. Experimental results obtained for a dislocation along [211] with for the six <220> type reflections using (g,5g) weak-beam conditions are summarised in the table below, together with the relevant values.

Multislice calculations of RHEED patterns from vicinal Si (001)

1993 ◽  
Vol 51 ◽  
pp. 1000-1001
Author(s):  
Scott Lordi
Keyword(s):  
Misorientation Angle ◽  
Incident Angle ◽  
Incident Beam ◽  
Experimental Results ◽  
Bragg Condition ◽  
Vicinal Surfaces ◽  
Kinematic Theory ◽  
Step Edges

Vicinal Si (001) surfaces are interesting because they are good substrates for the growth of III-V semiconductors. Spots in RHEED patterns from vicinal surfaces are split due to scattering from ordered step arrays and this splitting can be used to determine the misorientation angle, using kinematic arguments. Kinematic theory is generally regarded to be inadequate for the calculation of RHEED intensities; however, only a few dynamical RHEED simulations have been attempted for vicinal surfaces. The multislice formulation of Cowley and Moodie with a recently developed edge patching method was used to calculate RHEED patterns from vicinal Si (001) surfaces. The calculated patterns are qualitatively similar to published experimental results and the positions of the split spots quantitatively agree with kinematic calculations.RHEED patterns were calculated for unreconstructed (bulk terminated) Si (001) surfaces misoriented towards [110] ,with an energy of 15 keV, at an incident angle of 36.63 mrad ([004] bragg condition), and a beam azimuth of [110] (perpendicular to the step edges) and the incident beam pointed down the step staircase.

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