Absorption length for photon propagation in highly dense colloidal dispersions

1998 ◽  
Vol 13 (12) ◽  
pp. 3463-3467 ◽  
Author(s):  
Rajeev Garg ◽  
Robert K. Prud'homme ◽  
Ilhan A. Aksay ◽  
Feng Liu ◽  
Robert R. Alfano
Keyword(s):  
Light Transmission ◽  
Continuous Phase ◽  
Colloidal Dispersions ◽  
Interparticle Spacing ◽  
Absorption Length ◽  
Photon Propagation ◽  
High Particle Concentration ◽  
High Particle ◽  
Interparticle Separation ◽  
The Difference

The absorption length for photon propagation in highly concentrated colloidal dispersions calculated from temporal intensity profiles of 100 femto-second pulses is much longer than the absorption length obtained from the measurements of static light transmission in the pure continuous phase fluid. The difference between these two values is explained on the basis of small interparticle spacing at high particle concentration and hence shorter paths traveled by photons through the absorbing medium relative to the total diffusive path in the dispersion. The two values are in good agreement when the absorption length is rescaled with the interparticle separation.

Radiative Transfer in Packed Fluidized Beds: Dependent Versus Independent Scattering

1982 ◽  
Vol 104 (4) ◽  
pp. 573-579 ◽  
Author(s):  
M. Q. Brewster ◽  
C. L. Tien
Keyword(s):  
Radiative Transfer ◽  
Particle Concentration ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Interparticle Spacing ◽  
Particle Volume ◽  
Transfer Mode ◽  
High Particle Concentration ◽  
High Particle ◽  
Theoretical Predictions

Experimental measurements are compared with theoretical predictions for radiative transfer in suspensions of 11.0 μ dia Dow latex particles using 0.6328 μ He-Ne laser light. Both absorbing and nonabsorbing particles are studied with particle volume fraction ranging from 0.01 to 0.7 (close-packed). Predictions based on the classical assumptions that particles act as independent point scatterers are shown to give close agreement with experimental data even for close-packed conditions, as long as the interparticle clearance is greater than about 0.3 wavelengths. Evidence is presented indicating that interparticle spacing measured in wavelengths is the most critical parameter to gauge the importance of dependent scattering and that high particle concentration alone is no indication that scattering is dependent. The results have direct application to the design of packed/fluidized bed systems wherein thermal radiation is a significant heat transfer mode.

Capillary pressure, osmotic pressure and bubble contact areas in foams

Soft Matter ◽  
2021 ◽  
Author(s):  
Reinhard Höhler ◽  
Jordan Seknagi ◽  
Andrew Kraynik
Keyword(s):  
Osmotic Pressure ◽  
Capillary Pressure ◽  
Continuous Phase ◽  
Dispersed Phase ◽  
Average Pressure ◽  
Contact Areas ◽  
The Difference

The capillary pressure of foams and emulsions is the difference between the average pressure in the dispersed phase and the pressure in the continuous phase.

Theoretical Models of Cooperative Dynamics Near the Glass Transition

1990 ◽  
Vol 215 ◽  
Author(s):  
Josef Jäckle
Keyword(s):  
Glass Transition ◽  
Lattice Gas ◽  
Finite Size ◽  
Theoretical Models ◽  
Lattice Gases ◽  
Bootstrap Percolation ◽  
Square Lattice ◽  
High Particle Concentration ◽  
High Particle ◽  
Percolation Problem

AbstractIt is shown that diffusion in the hard-square and hard-octahedron lattice gases at high particle concentration has cooperative properties resembling molecular relaxation in undercooled liquids near the glass transition. For these models a characteristic length of cooperativity is introduced by an underlying percolation problem, which determines whether permanently blocked particles exist in lattices of finite size. The percolation problem belongs to a general class of bootstrap percolation models. Salient Monte Carlo results for the concentration and size dependence of self diffusion in the hard-square lattice gas are presented. Similarities with the n-spin facilitated kinetic Ising models are also pointed out.

scholarly journals Clusters of intramembrane particles associated with binding sites for alpha-bungarotoxin in cultured chick myotubes.

1979 ◽  
Vol 82 (2) ◽  
pp. 494-516 ◽  
Author(s):  
S A Cohen ◽  
D W Pumplin
Keyword(s):  
Acetylcholine Receptors ◽  
High Concentration ◽  
High Particle Concentration ◽  
High Particle ◽  
Cholinergic Synapses ◽  
Muscle Cultures ◽  
High Concentrations ◽  
Nerve Muscle ◽  
Alpha Bungarotoxin ◽  
Angular Particles

Developing chick myotubes in tissue culture were freeze-fractured to yield complementary replicas of large areas of membrane. Regions of muscle fibers with high concentrations of acetylcholine receptors were identified by binding of fluorescent-labeled alpha-bungarotoxin. Membranes in such regions contained clusters of large (100 A Diam) angular particles, similar in appearance to particles found in postsynaptic membranes of cholinergic synapses. Particles appeared in apposing areas of cytoplasmic and external leaflets but were more prevalent in the cytoplasmic leaflet. The areas of high particle concentration were coextensive with the fluorescence due to bound toxin. Treatment of cultures with tetrodotoxin increased the size of fluorescent spots and areas of high concentration of particles relative to those found in control cultures. In muscle cultures grown in the presence of spinal cord explants, some neurites contacted and innervated nearby myotubes. Intense fluorescence due to binding or alpha-bungarotoxin was present at portions of such neurite-myotube contacts. At these same portions, a high concentration of large angular particles was present in the sarcolemma adjacent to the neurite. In addition, an ordered arrangement of large particles was seen in the cytoplasmic leaflet of the neuronal plasmalemma directly apposing the muscle. The possible significance of these arrangements is discussed. Clusters on myotubes tended to be larger (contain more particles) when they occurred in groups, defined as three or more clusters with an intercluster distance of less than 0.5 micrometers. Clusters were also larger in myotubes treated with tetrodotoxin and in myotubes adjacent to some neurites in nerve-muscle cocultures. Several depressions containing particles similar to those in the clusters were found in the sarcolemma. The implications of these depressions are discussed in light of current theories of incorporation of proteins into cell membranes.

scholarly journals Empirical Approach to the Estimating the Immunity of Phase Modulation Signals with Continuous Phase

2020 ◽  
Vol 19 (6) ◽  
pp. 1280-1306
Author(s):  
Sergey Dvornikov ◽  
Sergey Dvornikov
Keyword(s):  
Phase Modulation ◽  
Noise Immunity ◽  
Approximation Error ◽  
Continuous Phase ◽  
Empirical Approach ◽  
Continuous Phase Modulation ◽  
Compact Representation ◽  
Temporal Properties ◽  
Shift Keying ◽  
The Difference

The high spectral efficiency of signals with continuous phase modulation (CPM) has determined their popularity and active use in various radio engineering projects. The uniqueness of the properties of CPM signals is associated with the preservation of the continuity of their phase when changing information messages for the duration of a symbol. At the same time, until recently, of the entire wide class of signals with continuous phase modulation, the most widespread were various variations, the so-called Minimum Shift Keying (MSK) signals. However, these are far from the only representatives of the class of CPM signals with the property of high spectral compactness. This article examines no less interesting signals of this class, formed by means of Dual Phase Modulation (DPM). In particular, analytical expressions of their synthesis are presented, their belonging to the class of CPM signals is substantiated. In addition, the article investigates the temporal properties of the phase function recommended by ITU-R SM.328-11 for the synthesis of signals with continuous phase modulation, presents the time and frequency fragments of MSK signals in comparison with signals with Binary Phase Shift Keying (BPSK). The stages of the analytical derivation of the model of noise immunity of PCM signals in terms of the probability of a bit error based on an empirical approach are presented. The generality of the obtained model with the known expression for MSK signals is shown by studying the difference function of the approximation error (error of the order of 10-3), which made it possible to obtain a more compact representation of the developed model in relation to DPM signals. It has been proven that DPM signals have higher noise immunity properties in relation to MSK signals (about 0.5 dB at an error level of 10-5), using the results of studying the difference functions determined by the difference between the signal symbols corresponding to the information values "1" and "0". The directions of further research are determined.

scholarly journals PRODUCTIVIDAD PRIMARIA EN LA CIENAGA GRANDE DE SANTA MARTA, COLOMBIA

2016 ◽  
Vol 19 ◽  
Author(s):  
Carlos A. Hernández J. ◽  
Klaus Gocke
Keyword(s):  
Primary Productivity ◽  
Coastal Lagoon ◽  
Mean Value ◽  
High Concentration ◽  
Water Turbidity ◽  
High Particle Concentration ◽  
High Particle ◽  
Wide Range ◽  
The Mean ◽  
The Caribbean

Between January 1987 and January 1988 the primary productivity and related parameters were studied in the Ciénaga Grande de Santa Marta. The Ciénaga is a coastal lagoon with an area of 423 km'2 and mean depth of 1.6 m, which is located at the Caribbean coast of Colombia. The salinity fluctuates seasonally within a wide range. The system is characterized by a high concentration of seston and a great primary productivity. The concentration of chlorophyll " a " ranged from 5.6to 181 ug Ii , the mean value was 59 ug I i . The concentration of proteins was within the extremes of 0.9 and 9.5 mg I"i f the mean value was 4.2 mg I ] . The gross primary productivity in the central part of the Ciénaga amounted to 1690 g C m*2 per year. Considering the temporal fluctuation in the whole system the lowest and highest values were 1.40 and 16.3 g C rrr2 per day. Highest productivity values were encountered when the salinity was low. The primary productivity is controlled by water turbidity and availability of nutrients, thus, seasonal continental waters. The photosynthetic laver ¡s restricted to less than 1.5 m due to the high particle concentration. The mean N: P relation was 4:1 which indicates that the nitrogen compounds are the limiting nutrientes. The high primary productivity sustains an important local fishery. The coastal area in the vicinity of the Ciénaga Grande is benefitted by the export of particulated and dissolved organic matter produced in excess within the coastal lagoon.

Friction and Lubrication Behavior of a Selective Laser Melted Hydraulic Spool Valve Under Contaminated Conditions

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Hongqin Ding ◽  
Peng Lu ◽  
Chao Zhang ◽  
Yi Zhu ◽  
Huayong Yang
Keyword(s):  
Particle Concentration ◽  
Sample Surface ◽  
Valve Body ◽  
Small Surface ◽  
Lubrication Regimes ◽  
High Particle Concentration ◽  
High Particle ◽  
Spool Valve ◽  
Surface Pores ◽  
Friction And Lubrication

Abstract Selective laser melting (SLM) technology has a great potential to reduce size and weight of hydraulic valves. However, the tribological performance of an SLMed valve has not been studied which is crucial for the performance and reliability of the valve, especially under contaminated conditions. In this study, the friction and lubrication behavior between an SLMed valve body and a traditional spool were studied using a scaled reciprocating test rig under various contaminated conditions (frequency at 5 Hz and 25 Hz; particle concentration at 0.4 mg/ml and 4 mg/ml; particle size at 1.6 µm and 15 µm). Three types of SLMed samples were fabricated using different exposure times: one has many large surface pores (pores area > 1000 µm2 accounts for 7.167% of the sample surface); one has a few small surface pores (pores area between 100 µm2 and 1000 µm2 accounts for 0.574% of the sample surface); and one only has micropores (pores area < 300 µm2 accounts for 0.168% of the sample surface). The density, hardness, microstructures, and pore characterization of the SLMed samples were investigated. The results indicated that the frequency greatly influenced friction and lubrication behaviors by determining lubrication regimes. The influence of surface pores on the lubrication and friction depends on contact conditions: pores which served as particle containers to reduce friction are prominent under 5 Hz frequency and high particle concentration; extra lubrication by the surface pores is observed under 25 Hz frequency and low particle concentration.

scholarly journals Sustainable Ambient Environment to Prevent Future Outbreaks: How Ambient Environment Relates to COVID-19 Local Transmission in Lima, Peru

2020 ◽  
Vol 12 (21) ◽  
pp. 9277
Author(s):  
Tsai-Chi Kuo ◽  
Ana Maria Pacheco ◽  
Aditya Prana Iswara ◽  
Denny Dermawan ◽  
Gerry Andhikaputra ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Multivariate Regression ◽  
Moving Average ◽  
Observation Time ◽  
Lessons Learned ◽  
Ambient Environment ◽  
High Particle Concentration ◽  
High Particle ◽  
Global Issue ◽  
Moving Average Model

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), universally recognized as COVID-19, is currently is a global issue. Our study uses multivariate regression for determining the relationship between the ambient environment and COVID-19 cases in Lima. We also forecast the pattern trajectory of COVID-19 cases with variables using an Auto-Regressive Integrated Moving Average Model (ARIMA). There is a significant association between ambient temperature and PM10 and COVID-19 cases, while no significant correlation has been seen for PM2.5. All variables in the multivariate regression model have R2 = 0.788, which describes a significant exposure to COVID-19 cases in Lima. ARIMA (1,1,1), during observation time of PM2.5, PM10, and average temperature, is found to be suitable for forecasting COVID-19 cases in Lima. This result indicates that the expected high particle concentration and low ambient temperature in the coming season will further facilitate the transmission of the coronavirus if there is no other policy intervention. A suggested sustainable policy related to ambient environment and the lessons learned from different countries to prevent future outbreaks are also discussed in this study.

scholarly journals Comparison of silorane and methacrylate-based composite resins on the curing light transmission

2010 ◽  
Vol 21 (6) ◽  
pp. 538-542 ◽  
Author(s):  
Ricardo Danil Guiraldo ◽  
Simonides Consani ◽  
Rafael Leonardo Xediek Consani ◽  
Sandrine Bittencourt Berger ◽  
Wilson Batista Mendes ◽  
...  
Keyword(s):  
Composite Resin ◽  
Light Transmission ◽  
Knoop Hardness ◽  
Composite Resins ◽  
Power Meter ◽  
Light Curing ◽  
Curing Light ◽  
The Mean ◽  
Spectral Distributions ◽  
The Difference

The aim of this study was to investigate the influence of different composite resins - Filtek P90 (silorane-based composite) and Heliomolar (methacrylate-based composite) - on light transmission and decrease in Knoop hardness between the bottom and top of cured specimens. The irradiance of a light-curing unit (LCU) was measured with a power meter (Ophir Optronics; 900 mw/cm2) and spectral distributions were obtained using a spectrometer (USB 2000). Twenty standardized cylindrical specimens (2 mm thick x 7 mm diameter) of each composite resin were obtained by curing using the LCU for 40 s. Light energy transmission through the composite was calculated (n=10). The Knoop hardness number for each surface was recorded as the mean of 3 indentations. The difference in Knoop hardness between the top and bottom (DKH) of the same specimen was calculated (n=10). The irradiance of light that passed through Filtek P90 (272 mW/cm2) was not significantly greater than that the passed through Heliomolar (271 mW/cm2). The DKH of Filtek P90 (25%) was significantly higher than that of Heliomolar (12%). There was a greater degree of subsurface polymerization of the methacrylate-based composite compared to the silorane-based composite.

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