Transfilter induction of kidney tubules as a function of the extent and duration of intercellular contacts

Development ◽  
1978 ◽  
Vol 47 (1) ◽  
pp. 97-109
Author(s):  
Lauri Saxén ◽  
Eero Lehtonen
Keyword(s):  
Pore Size ◽  
Filter Material ◽  
Culture Conditions ◽  
Kidney Tubules ◽  
Pore Density ◽  
Kidney Tubule ◽  
Intercellular Contacts ◽  
Cytoplasmic Processes ◽  
Kinetics Of

The kinetics of kidney tubule induction were examined in transfilter experiments by varying the time of transfilter apposition, the porosity and pore size of the filters, and the culture conditions. Transfilter contact between the interacting cells is established within an hour when cytoplasmic processes emerge through the interposed filter; then a further 16–24 h are needed for completion of induction. This lag is a function of thickness and pore size of the filter, and is not reduced by precultivation of the inductor on the filter. Material that accumulates on the far side of the filter during such cultivation displays no morphogenetic activity. The intensity of the mesenchymal response was roughly quantified and shown to be a function of pore size, pore density and duration of transfilter contact.

Demonstration of cytoplasmic processes in Millipore filters permitting kidney tubule induction

Development ◽  
1975 ◽  
Vol 33 (1) ◽  
pp. 187-203
Author(s):  
E. Lehtonen ◽  
J. Wartiovaara ◽  
S. Nordling ◽  
L. Saxén
Keyword(s):  
Spinal Cord ◽  
Kidney Tubules ◽  
Metanephric Mesenchyme ◽  
Kidney Tubule ◽  
Close Apposition ◽  
Cytoplasmic Material ◽  
Diffusion Studies ◽  
Induction System ◽  
Cytoplasmic Processes ◽  
Millipore Filters

The presence of cytoplasmic material inside thin Millipore filters between interacting mouse metanephric mesenchyme and spinal cord was investigated using different fixation methods. The transmission of induction was studied from sections of Zenker-fixed paraffin-embedded explants. Formation of kidney tubules was taken as evidence for induction. Filters with 0·8 and 0·22 μm pores permitted induction, whereas only 6 out of 31 filters with 0·1 μm. pores did so. Glutaraldehyde-fixed Epon-embedded explants were used for study of cytoplasmic penetration into filters. In thick sections, filters with large pores were seen to contain cytoplasmic material at all levels. Filters with 0·1 μm pores usually showed only shallow ingrowth, but those which had permitted passage of induction contained material at least half way from the spinal cord and shallow ingrowth from the mesenchyme. With 0·8 μm filters the ingrowths from both sides met first after 18 h of transfilter cultivation. This has previously been shown to be the minimum time needed for induction to take place in this system. In electron microscopy cytoplasmic processes were seen deep inside the 0·8 and 0·22 μm filters regularly permitting induction. In small pores such material was only preserved by certain glutaraldehyde fixatives. Diffusion studies did not reveal major differences between induction-permitting 0·22 μm filters and induction-preventing 0·1 μm filters. Thus in the kidney tubule induction system this and our previous work speak in favour of a mechanism based on close apposition of cells rather than on long-range diffusion of inductive substances or on matrix interaction.

Modeling the Irradiation Swelling of UO2 at the Fuel Pellet Rim

2013 ◽  
Author(s):  
Lijun Gao ◽  
Bingde Chen ◽  
Zhong Xiao ◽  
Shengyao Jiang ◽  
Jiyang Yu
Keyword(s):  
Pore Size ◽  
Fission Products ◽  
Transformation Process ◽  
Fuel Pellet ◽  
Published Data ◽  
Detailed Calculation ◽  
Pore Density ◽  
The Matrix ◽  
Swelling Rate ◽  
Modeling Code

Irradiation swelling of UO2 at the fuel pellet rim was modeled based on the published theory and data of HBS (High Burnup Structure) formation. Fuel swelling was divided into two parts: fuel matrix swelling and porosity growth. Both solid fission products and fission gas contribute to the fuel matrix swelling prior to HBS transformation, resulting in relatively stable matrix swelling rate of around 1.0% per 10 GWd/tU, but the transformation accompanied by Xe depletion reduces the matrix swelling rate to approximately 0.3% per 10 GWd/tU, only attributed to solid fission products. Considering the direct impact of Xe depletion on the drop of matrix swelling rate, the exponential law of Xe depletion was applied to model the reduction of matrix swelling rate. Pore size and pore density evolution are the two main aspects of porosity growth. Pore size takes the form of lognormal distribution, whose parameters are obtained through fitting the experimental data. Pore density increases in the transformation process but goes down as a result of pore coarsening thereafter. Published data of three pellets were used to verify the correlations modeling pore growth, which were proven generally consistent with each other. The results of this work are ready to be incorporated into fuel performance modeling code as an option for detailed calculation of fuel swelling.

scholarly journals IMMUNE RESPONSES IN VITRO

1971 ◽  
Vol 134 (2) ◽  
pp. 395-416 ◽  
Author(s):  
Carl W. Pierce ◽  
Barbara M. Johnson ◽  
Harriet E. Gershon ◽  
Richard Asofsky
Keyword(s):  
Culture Conditions ◽  
Antibody Concentration ◽  
Spleen Cells ◽  
Immunoglobulin Class ◽  
Cell Densities ◽  
Erythrocyte Antigen ◽  
First Time ◽  
Kinetics Of

We have demonstrated for the first time that mouse spleen cells stimulated in vitro with heterologous erythrocytes developed immunoglobulin class-specific γM, γ1, γ2a+2b, and γA plaque-forming cell (PFC) responses. A modification of the hemolytic plaque technique, the addition of goat anti-mouse µ-chain antibody to the assay preparation, specifically prevented development of all γM PFC and enabled accurate and reproducible enumeration of immunoglobulin class-specific PFC after treatment with appropriate monospecific anti-globulins and complement. Culture conditions, with regard to medium, atmosphere, agitation, and spleen cell densities, were similar to those previously shown to support only γM PFC responses. Evaluation of the kinetics of appearance of PFC showed that γM PFC reached maximum numbers on days 4–5; the magnitude of this response was 3–10 times greater than γ1 γ2a+2b, or γA PFC which reached maximum numbers on days 5–6. Optimal erythrocyte antigen dose for γM PFC responses was 107/culture, whereas a dose of 106 erythrocytes/culture consistently stimulated optimal γ1 γ2a+2b, or γA PFC responses. Investigations of the effects of anti-erythrocyte antibody on γM and γG PFC responses indicated that antibody suppressed these responses by neutralizing the effective antigenic stimulus at the macrophage-dependent phase of the response. At the same antibody concentration, γG PFC responses were more effectively suppressed than γM PFC responses. Further, γG responses could be almost completely suppressed by antibody as long as 48 hr after initiation of cultures, whereas γM PFC responses could only be completely suppressed during the first 24 hr. These results were discusssed in terms of the role of antigen in the stimulation γM and γG antibody.

Monodisperse Mesoporous Microparticles Prepared by Evaporation-Induced Self Assembly Within Aerosols

2003 ◽  
Vol 775 ◽  
Author(s):  
Shailendra Rathod ◽  
G. V. Rama Rao ◽  
Brett Andrzejewski ◽  
Gabriel P. López ◽  
Timothy L. Ward ◽  
...  
Keyword(s):  
Pore Size ◽  
Self Assembly ◽  
Swelling Agent ◽  
Aerosol Generator ◽  
Amphiphilic Molecules ◽  
Brij 58 ◽  
Evaporation Induced Self Assembly ◽  
Uptake Process ◽  
Hexagonally Ordered ◽  
Kinetics Of

AbstractEvaporation induced self assembly (EISA) within microdroplets produced by a vibrating orifice aerosol generator (VOAG) has been used to produce monodisperse mesoporous silica particles. This process exploits the concentration of evaporating droplets to induce the organization of various amphiphilic molecules, effectively partitioning the silica precursor (TEOS) to the hydrophilic regions of the structure. Promotion of silica condensation, followed by removal of the surfactant, provides ordered spherical mesoporous particles. Using the VOAG we have produced highly monodisperse particles in the 5 to 10 μm diameter range. The cationic surfactant CTAB typically leads to hexagonal mesostructure with mean pore size of about 2 nm and specific surface area around 900 m2/g. We have also shown that the pore size in CTABtemplated particles can be increased to 3.8 nm by incorporating trimethylbenzene as a swelling agent. The TMB prefentially locates inside and swells the hydrophobic regions of the surfactant mesostructure. Pore size can also be varied by the choice of amphiphile. Hexagonally ordered particles have been produced using the nonionic surfactant Brij-58 and block copolymer F127. These powders possessed mean pore size 2.8 nm and 6.9 nm, respectively. The uptake of alkyl pyridinium chloride molecules have recently been measured, revealing an uptake capacity that is explained by surface adsorption (as opposed to simple pore infiltration). Kinetics of the uptake process are still be analyzed.

scholarly journals Effect of ammonia treatment of wheat straw with or without supplementation of potato protein on intake, digestion and kinetics of comminution, rumen degradation and passage in steers

1994 ◽  
Vol 72 (1) ◽  
pp. 147-165 ◽  
Author(s):  
S. J. Oosting ◽  
P. J. M. Vlemmix ◽  
J. Van Bruchem
Keyword(s):  
Organic Matter ◽  
Pore Size ◽  
Wheat Straw ◽  
Latin Square ◽  
Potato Protein ◽  
Faecal Excretion ◽  
Rumen Degradation ◽  
Fractional Rate ◽  
Beet Pulp ◽  
Kinetics Of

Untreated wheat straw (UWS) or ammoniated wheat straw without (AWS) or with (AWSP) a supplement of potato protein of a low rumen degradability was fed to three steers according to a 3 × 3 Latin square design. All rations were supplemented with sugar-beet pulp and minerals. Voluntary organic matter intake (OMI, g/kg0.75 per d) was 67.8, 76.0 and 80.1 for whole rations (51.1, 59.7 and 59.2 for straw) for UWS, AWS and AWSP respectively, which was significantly higher for AWS and AWSP than for UWS. Organic matter digestibility (OMD, g/kg) was 561, 596 and 625 for the respective rations UWS, AWS and AWSP, also significantly higher for AWS and AWSP than for UWS. The increased voluntary intake and digestion of ammoniated wheat-straw-based rations were associated with a significantly higher potentially degradable fraction (D) of neutral detergent fibre (NDF) in offered straw (556 and 661 g/kg for untreated and ammoniated wheat straw respectively) and in the rumen pool (469, 555 and 554 g/kg for UWS, AWS and AWSP respectively). Isolated small rumen particles (retained on sieves with a pore size < 1.25 and > 0.041 mm) had a significantly lower D of NDF (average 588 g/kg) than isolated large rumen particles (average 663 g/kg). Fractional rates of degradation of NDF did not differ significantly either between untreated and ammonia-treated wheat straw offered (2.9 and 2.6%/h respectively) or between rumen pools (1.8, 1.7 and 2.1 %/h for UWS, AWS and AWSP respectively). Rations based on ammoniated wheat straw had a significantly higher rumen NH3-N concentration than UWS. Although the rumen pool size of total contents differed significantly between treatments, those of dry and organic matter and of cell wall constituents were not significantly different. The proportion of rumen dry matter passing through a sieve with a pore size of 1.25 mm averaged 0.684 over rations (not significantly different between rations). Daily rumination (96 min) and eating (52 min) times/kg NDF ingested did not differ between rations. The rate of comminution of large particles estimated from the disappearance of indigestible NDF in large rumen particles from the rumen of animals without access to feed was 4.1, 6.3 and 7.1 %/h for UWS, AWS and AWSP respectively. These values were not significantly different. The fractional rate of passage estimated from the faecal excretion of Cr-NDF was 5.4, 6.1 and 6.3%/h for UWS, AWS and AWSP respectively (significantly higher for AWS and AWSP than for UWS) but the turnover rate of indigestible NDF did not differ between treatments.

Research on the Porosity and Pore Size of Spun-Bonded Fabrics Based on Matlab7.0 Image Processing Technology

2012 ◽  
Vol 601 ◽  
pp. 99-104 ◽  
Author(s):  
Ru Fang Yuan ◽  
Yong Yang Wang ◽  
Cheng Yan Zhu
Keyword(s):  
Image Processing ◽  
Pore Structure ◽  
Pore Size ◽  
Pore Volume ◽  
Average Pore Size ◽  
Filter Material ◽  
Test Method ◽  
Processing Technology ◽  
Filter Performance ◽  
Image Processing Technology

The image with high resolution was obtained through scanning the spun-bonded fabric, and processed with the help of Matlab7.0 software to calculate the pore structure of the spun-bonded fabric. On the basis of the relationship between number of pixels and area, the porosity and average pore size of spun-bonded fabric were analyzed; pore size and porosity were calculated by using the equation method and the air bubble test method as well. By comparing the data of the two methods, the correlation between them was gotten. Finally, it was shown that using the image processing technology to research the pore structure of spun-bonded fabric was a feasible way. There are various factors affecting the performance of textile filtering materials, and the porosity and pore size of the fabrics play an important role in filtration. As is known to all, fabric porosity and pore size are indicators to measure the size of fabric pore volume, one is the ratio of pore volume with the total fabric volume, and the other one refers to the average diameter of the holes in the textile filter material. They directly affect the permeability, the hydraulic conductivity of the fabric and the ability to prevent the particles getting through. Generally speaking, the bigger the porosity and pore size, the greater the permeability coefficient and the better the permeability of the filter material. Porosity and pore size directly affect the product's function and application. Therefore, the pore structure has a great impact on textile filter performance [1]. Nowadays, the formula method was generally used to calculate the porosity, and the bubble method was always used in testing pore size.

The microstructure and dealloying kinetics of a Cu-Mn alloy

1994 ◽  
Vol 9 (11) ◽  
pp. 2878-2883 ◽  
Author(s):  
Un-Sig Min ◽  
James C.M. Li
Keyword(s):  
Pore Size ◽  
Annealed Specimen ◽  
Nacl Solution ◽  
Porous Copper ◽  
Phase Inhomogeneity ◽  
Rolled Specimen ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Cold Rolled Specimen

Porous copper was produced by electrolytic dealloying of a Cu-Mn alloy (Incramute: Cu, 40-48 wt. % Mn, 1.4-2.3 wt. % Al) conducted in a 0.3 N-NaCl solution at a potential of −0.2 V (SCE). The dealloying time needed for the as-received cold-rolled specimen (50 h) is shorter than that of the annealed specimen (850 °C for 2 h). The pore size, about 1 μm, of the dealloyed cold-rolled specimen is bigger than that, about 0.1 μm, of the dealloyed specimen after annealing. This is probably because annealing reduced the phase inhomogeneity and removed the rolling effects.

scholarly journals Kinetics of pore size during irreversible electrical breakdown of lipid bilayer membranes

1993 ◽  
Vol 64 (1) ◽  
pp. 121-128 ◽  
Author(s):  
C. Wilhelm ◽  
M. Winterhalter ◽  
U. Zimmermann ◽  
R. Benz
Keyword(s):  
Pore Size ◽  
Lipid Bilayer ◽  
Electrical Breakdown ◽  
Lipid Bilayer Membranes ◽  
Bilayer Membranes ◽  
Kinetics Of

scholarly journals Effect of Pore Size on the Biodegradation Rate of Silk Fibroin Scaffolds

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Zuwei Luo ◽  
Qin Zhang ◽  
Meijing Shi ◽  
Yang Zhang ◽  
Wei Tao ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Weight Loss ◽  
Pore Size ◽  
Silk Fibroin ◽  
Degradation Rate ◽  
Structural Integrity ◽  
Pore Density ◽  
Tissue Engineering Scaffolds ◽  
Silk Scaffolds

Controlling the degradation rate of silk fibroin-based biomaterial is an important capability for the fabrication of silk-based tissue engineering scaffolds. In this study, scaffolds with different pore sizes were prepared by controlling the freezing temperature and the silk fibroin concentration.In vitrodegradation results showed that the internal pore walls of the scaffolds with a larger pore size collapsed upon exposure to collagenase IA for times ranging from 6 to 12 days, and the silk scaffolds exhibited a faster rate of weight loss. The morphological and structural features of the silk scaffolds with a smaller pore size maintained structural integrity after incubation in the protease solution for 18 days, and the rate of weight loss was relatively slow. Scaffolds with a smaller pore size or a higher pore density degraded more slowly than scaffolds with a larger pore size or lower pore density. These results demonstrate that the pore size of silk biomaterials is crucial in controlling the degradation rate of tissue engineering scaffolds.

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