Infrared study of goethites of varying crystallinity and particle size: II. Crystallographic and morphological changes in series of synthetic goethites

Clay Minerals ◽  
1986 ◽  
Vol 21 (2) ◽  
pp. 201-210 ◽  
Author(s):  
P. Cambier
Keyword(s):  
Particle Size ◽  
Morphological Changes ◽  
Unit Cell ◽  
Infrared Study ◽  
In Series ◽  
A Minor ◽  
Absorbance Band ◽  
Low Crystallinity

AbstractLow crystallinity of unsubstituted goethites is characterized by a small coherently diffracting domain, which may be accompanied by another type of disorder revealed by broader IR half-absorbance band widths. Inside the unit cell, the H-bond is weaker, which increases the OH stretching frequency and lowers the bending frequencies. Also, an increase in parameter a and a change in Fe-O bonds, which might correspond to a minor tilting of octahedra, occur along with a lowering of the frequency of the 630 cm−1 band.

Producing Steam by Spraying Water on a Heated Bed of Steel Spheres

2021 ◽  
pp. 1-42
Author(s):  
D. Jordan Bouchard ◽  
HengSheng Yang ◽  
Sanjeev Chandra
Keyword(s):  
Particle Size ◽  
Thermal Mass ◽  
Steam Generation ◽  
Bed Porosity ◽  
The Media ◽  
Effect Of Particle Size ◽  
The Difference ◽  
Rate Of Evaporation ◽  
A Minor ◽  
Counter Current

Abstract Steam generators used in industrial baking ovens operate by pouring or spraying water on a preheated thermal mass. This paper presents a methodology to quantify the amount of steam generated from a thermal mass along with experiments to determine the effect of particle size and porosity on steam generation. Three sizes of steel spheres, 0.6 mm, 8 mm, and 16 mm in diameter, were used to construct porous media beds that were preheated in an oven after which water was sprayed onto them from a full-cone nozzle for a fixed duration. The weight of the heated bed and the impinging water were recorded during spraying. The difference in weight change when spraying on heated and unheated beds gave the rate of evaporation. Thermocouples were used to record the internal temperature of the bed. Steam generation rate increased with particle size while bed porosity had only a minor influence. The counter-current flow of steam within the media bed disrupts the downward flow of water enough to leave pockets of hot material, reducing steam production. To maximize steam generation the media size, material, and spray time should be matched to ensure the surfaces of particles remain above the boiling point of water during spraying.

scholarly journals Pyrene-based aggregation-induced emission luminogens (AIEgen): structure correlated with particle size distribution and mechanochromism

2019 ◽  
Vol 7 (23) ◽  
pp. 6932-6940 ◽  
Author(s):  
Xing Feng ◽  
Jun Zhang ◽  
Zhen Hu ◽  
Qingsong Wang ◽  
Md. Monarul Islam ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Significant Role ◽  
Emission Intensity ◽  
Morphological Changes ◽  
Nano Particle ◽  
Aggregation Induced Emission ◽  
Water Fraction ◽  
Particle Species

The morphology of pyrene-based AIEgens changes depending on the water fraction. The different size distribution and morphological changes of nano-particle species play a significant role in enhancing the emission intensity in the aggregated state.

Series elasticity of urinary bladder smooth muscle

1976 ◽  
Vol 231 (5) ◽  
pp. 1337-1342 ◽  
Author(s):  
RS Alexander
Keyword(s):  
Elastic Stiffness ◽  
Bladder Smooth Muscle ◽  
Bladder Tissue ◽  
Series Elasticity ◽  
Quick Release ◽  
Contractile System ◽  
Urinary Bladder Smooth Muscle ◽  
In Series ◽  
A Minor

Loops of rat bladder were stretched between pins in vitro, supported by a clamp that could be suddenly shortened by activation of a solenoid to achieve a quick release of tension. The series elasticity measured in this fashion was found to follow an exponential course and to be modified by the rate of release, indicating a minor viscous component. Tissue length decreased and series elastic stiffness appeared to increase with muscle contraction, but no alteration in series elasticity was evident when the data were related to the tension existing in the tissue at the moment of quick release. Inactivation of the contractile system by removing calcium ion with ethylene glycol-bis-(beta-aminoethylether)-N,N'-tetraacetate (EGTA) similarly did not alter series elasticity when it was related to the tension existing in the tissue. Series elasticity during the stress relaxation following a stretch, and during the contracting and relaxing phases of rhythmic contractions, was also determined by tissue tension. The conclusion drawn is that contractile cross bridges do not contribute to the series elasticity measured in bladder tissue.

A Structure-Based Biomechanical Model for the Effect of Dissolution of Muscle Cells on Pig Arteries: Elastin Associated With Muscle and Extracellular Matrix

2011 ◽  
Author(s):  
Aristotelis Agianniotis ◽  
Alexander Rachev ◽  
Nikos Stergiopulos
Keyword(s):  
Extracellular Matrix ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Biomechanical Model ◽  
Muscle Cells ◽  
In Series ◽  
Minor Part ◽  
The Media ◽  
The One ◽  
A Minor

We developed a structure-based model of the arterial wall to explain the effect of dissolution of smooth muscle cells (SMC) on the mechanical behavior of the artery and to obtain a better understanding of the interaction between the different wall components. Pressure-radius curves and dimensions of zero-stress configuration were measured in 5 control and 5 decellularized porcine common carotid arteries. We found that 13% of elastin is associated with the smooth muscle cells (SMC) whereas the rest 87% is associated with the extracellular matrix (ECM). Further, we found that the elastin related to SMC and the one related to the ECM have circumferential prestretches of 2.04 and 0.89, respectively. We conclude that the majority of elastic in the media is linked to ECM and is under compression at zero load, whereas a minor part is linked to VSM and is under tension (SMC related) at its zero load state. Upon chemical dissolution of the muscle cells elastin in series with SMC do not bear load allowing elastin connected to ECM to release its compressive prestress, leading to the expansion of the artery.

Mineralogical Problems in X-Ray Emission Analysis of Sylvite Concentrates

1963 ◽  
Vol 7 ◽  
pp. 555-565
Author(s):  
Frank Bernstein
Keyword(s):  
Particle Size ◽  
Atomic Number ◽  
Size Effects ◽  
Quantitative Relationship ◽  
Minor Constituent ◽  
Emission Analysis ◽  
X Ray ◽  
Particle Size Effects ◽  
Chemical Combination ◽  
A Minor

AbstractMineralogical effects, which relate to the occurrence of an element in different forms of chemical combination, often are a problem to the X-ray analyst since these forms usually differ in X-ray sensitivity. An example of this is cited in connection with the analysis of sylvite concentrates for potassium. An evaluation is made of mineralogical effects and a quantitative relationship between X-ray intensity and mineral form and particle size is derived. If the particle size of a minor constituent is reduced sufficiently the mineralogical effect disappears. Target materials for X-ray sources are found to have only minor effects on relative intensities of different compounds of an element. Finally, it is concluded that the advantages of higher intensities gained through the use of target materials close in atomic number to the material being analyzed far outweigh particle size effects which are shown to be relatively small.

Recycling Scrap Crosslinked Urethane Polymers

1975 ◽  
Vol 48 (5) ◽  
pp. 972-980 ◽  
Author(s):  
R. M. Gerkin ◽  
F. E. Critchfield ◽  
W. A. Miller ◽  
R. Roberts ◽  
C. G. Seefried
Keyword(s):  
Particle Size ◽  
Ambient Temperature ◽  
Size Reduction ◽  
Minor Effect ◽  
Particle Size Reduction ◽  
Foam Formulation ◽  
A Minor ◽  
High Degree ◽  
Sulfur Curing

Abstract A. Scrap LRM polymers can be ground to powder on the Banbury operating at ambient temperature with cooling of the rotors and jacket. Particle size reduction can be accomplished in 5 min at 180 rpm. B. Powdered LRM polymer can be blended with TPU up to 50 wt.% and the composite compression molded to give the same properties as the TPU. C. Powdered LRM polymer can be blended with nitrile, chloroprene, and EPDM rubbers to give incompatible composites. The powdered LRM polymer acts in a manner similar to typical nonreinforcing fillers. D. It is possible to degrade powdered LRM polymers to a tacky mass at 180°C, which behaves much like a typical extender oil, when blended with nitrile and chloroprene rubbers. It is speculated that the degraded urethane should show a high degree of permanency in such blends. E. Addition of the urethane polymer to the rubber stocks does not interfere with the standard sulfur-curing mechanisms. F. Scrap HR foam can be ground to a powder in the Banbury in a manner similar to LRM scrap. G. A blend of 5 phr of powdered foam with a new HR foam formulation was machine processable. Addition of the powder had only a minor effect on the properties of the new foam.

Strain Driven Two-Dimensional Phase Transition in PbSnF4 Superionic Conductor

1994 ◽  
Vol 369 ◽  
Author(s):  
Georges Denes ◽  
M.C. Madamba ◽  
J.M. Parris
Keyword(s):  
Phase Transition ◽  
Structural Change ◽  
Chemical Composition ◽  
Lead Nitrate ◽  
Unit Cell ◽  
Minor Amount ◽  
Two Dimensional ◽  
Detectable Change ◽  
A Minor ◽  
Nonuniform Strain

AbstractWhen a minor amount of HF is added to the SnF2 reacted with lead nitrate in aqueous solutions to prepare PbSnF4, a phase transition from tetragonal α-PbSnF4 to orthorhombíc o-PbSnF4 takes place. The transition is essentially bidimensional and takes place in the (a,b) plane of the unit-cell. The compactness of the structure increases at the transition. No essential structural change occurs: the transition is most likely displacive and it is driven by bidimensional nonuniform strain acting along the aand baxes of the unit-cell. This transition is similar to ferroic transitions (in this case, paraelastic → ferroelastic). No detectable change of chemical composition occurs at the transition, and the reason why the presence of HF in the reaction mixture causes the transition remains unknown.

scholarly journals Surface energy of nanoparticles – influence of particle size and structure

2018 ◽  
Vol 9 ◽  
pp. 2265-2276 ◽  
Author(s):  
Dieter Vollath ◽  
Franz Dieter Fischer ◽  
David Holec
Keyword(s):  
Molecular Dynamics ◽  
Particle Size ◽  
Surface Energy ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Definition Of ◽  
Dynamics Simulations ◽  
Classical Thermodynamics ◽  
A Minor

The surface energy, particularly for nanoparticles, is one of the most important quantities in understanding the thermodynamics of particles. Therefore, it is astonishing that there is still great uncertainty about its value. The uncertainty increases if one questions its dependence on particle size. Different approaches, such as classical thermodynamics calculations, molecular dynamics simulations, and ab initio calculations, exist to predict this quantity. Generally, considerations based on classical thermodynamics lead to the prediction of decreasing values of the surface energy with decreasing particle size. This phenomenon is caused by the reduced number of next neighbors of surface atoms with decreasing particle size, a phenomenon that is partly compensated by the reduction of the binding energy between the atoms with decreasing particle size. Furthermore, this compensating effect may be expected by the formation of a disordered or quasi-liquid layer at the surface. The atomistic approach, based either on molecular dynamics simulations or ab initio calculations, generally leads to values with an opposite tendency. However, it is shown that this result is based on an insufficient definition of the particle size. A more realistic definition of the particle size is possible only by a detailed analysis of the electronic structure obtained from initio calculations. Except for minor variations caused by changes in the structure, only a minor dependence of the surface energy on the particle size is found. The main conclusion of this work is that surface energy values for the equivalent bulk materials should be used if detailed data for nanoparticles are not available.

scholarly journals Survival, growth, and morphology of blue king crabs: effect of ocean acidification decreases with exposure time

2016 ◽  
Vol 74 (4) ◽  
pp. 1033-1041 ◽  
Author(s):  
William Christopher Long ◽  
Scott B. Van Sant ◽  
Katherine M. Swiney ◽  
Robert J. Foy
Keyword(s):  
Mortality Rate ◽  
Ocean Acidification ◽  
Morphological Changes ◽  
Phenotypic Variability ◽  
Minor Effect ◽  
King Crab ◽  
Growth And Survival ◽  
Blue King Crab ◽  
Paralithodes Platypus ◽  
A Minor

Ocean acidification is an altering marine carbonate chemistry resulting in potential effects to marine life. In this study, we determine the effects of decreased pH on the morphology, growth, and survival of juvenile blue king crab, Paralithodes platypus. Crabs were reared at three pH levels: ambient (control, pH ∼8.1), pH 7.8, and pH 7.5, for 1 year and monitored for morphological changes, survival, and growth. Exposure to seawater at pH 7.8 had no effect on morphology or mortality and had only a minor effect on growth compared with the ambient treatment. However, exposure to seawater at pH 7.5 substantially increased mortality and decreased growth compared with the ambient treatment. The best fit model of mortality rate at pH 7.5 showed an initially high mortality rate, which dropped to become comparable to the mortality rate in the other treatments. This suggests phenotypic variability or plasticity in juveniles and may indicate acclimation by blue king crab to ocean acidification. As such, blue king crab may have scope for evolutionary adaptation in response to gradually changing pH levels. However, effects on other life-history stages, sub-lethal effects, carryover or transgenerational effects, and interactions with other stressors, such as increased temperature, still need to be investigated.

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