HPM‐16, a New Stable Interrupted Zeolite with a Multidimensional Mixed Medium‐Large Pore System Containing Supercages

Horseradish peroxidase (mol. diam. ≃50 A) and ferritin (mol. diam. ≃110 A) were used as probe molecules for the small and large pore system, respectively, in blood capillaries of the intestinal mucosa of the mouse. Peroxidase distribution was followed in time, after intravenous injection, by applying the Graham-Karnovsky histochemical procedure to aldehyde-fixed specimens. The tracer was found to leave the plasma rapidly and to reach the pericapillary spaces 1 min post injection. Between 1 min and 1 min 30 sec, gradients of peroxidase reaction product could be demonstrated regularly around the capillaries; their highs were located opposite the fenestrated parts of the endothelium. These gradients were replaced by even distribution past 1 min 30 sec. Ferritin, followed directly by electron microscopy, appeared in the pericapillary spaces 3–4 min after i.v. injection. Like peroxidase, it initially produced transient gradients with highs opposite the fenestrated parts of the endothelium. For both tracers, there was no evidence of movement through intercellular junctions, and transport by plasmalemmal vesicles appeared less efficient than outflow through fenestrae. It is concluded that, in the blood capillaries of the inintestinal mucosa, the diaphragms of the endothelial fenestrae contain the structural equivalents of the small pore system. The large pore system seems to be restricted to a fraction of the fenestral population which presumably consists of diaphragm-free or diaphragm-deficient units.

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Plasmalemmal vesicles represent the large pore system of continuous microvascular endothelium

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1993.265.2.h725 ◽

1993 ◽

Vol 265 (2) ◽

pp. H725-H733 ◽

Cited By ~ 23

Author(s):

D. Predescu ◽

G. E. Palade

Keyword(s):

Intercellular Junctions ◽

Pore System ◽

Microvascular Endothelium ◽

Plasmalemmal Vesicles ◽

Morphological Studies ◽

Large Pore ◽

In Transit

In the capillary physiology literature, molecules and particles larger than 10 nm are assumed to leave the plasma mostly through large pores located at the level of intercellular junctions in microvessels lined with a continuous endothelium. In morphological studies of similar microvessels, outgoing particles > 10 nm were detected in endothelial plasmalemmal vesicles not in intercellular junctions. Because the probes may not be found in transit through the junctions because they may be swept away by strong currents generated by Starling forces, we have examined a large number of junctions in arteriolar, capillary, and venular segments of bipolar vascular fields of mouse diaphragms collected after perfusion with large pore probes. The results presented in this study indicate that 1) the perfused probes accumulate in the luminal introits of the junctions as filtration residues that decrease in size and frequency from arterioles to venules, and 2) large pore probes move across the endothelium exclusively through plasmalemmal vesicles.

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Transport properties of alveolar epithelium measured by molecular hetastarch absorption in isolated rat lungs

Journal of Applied Physiology ◽

10.1152/jappl.2001.91.4.1730 ◽

2001 ◽

Vol 91 (4) ◽

pp. 1730-1740 ◽

Cited By ~ 10

Author(s):

Robert L. Conhaim ◽

Kal E. Watson ◽

Stephen J. Lai-Fook ◽

Bruce A. Harms

Keyword(s):

Molecular Weight ◽

Transport Properties ◽

High Molecular Weight ◽

Pore Radius ◽

Alveolar Epithelium ◽

Low Molecular Weight ◽

Pore System ◽

Large Pore ◽

Small Pore ◽

Isolated Rat

To evaluate the transport properties of the alveolar epithelium, we instilled hetastarch (Het; 6%, 10 ml, 1 − 1 × 104kDa) into the trachea of isolated rat lungs and then measured the molecular distribution of Het that entered the lung perfusate from the air space over 6 h. Het transport was driven by either diffusion or an oncotic gradient. Perfusate Het had a unique, bimodal molecular weight distribution, consisting of a narrow low-molecular-weight peak at 10–15 kDa (range, 5–46 kDa) and a broad high-molecular-weight band (range 46–2,000 kDa; highest at 288 kDa). We modeled the low-molecular-weight transport as (passive) restricted diffusion or osmotic flow through a small-pore system and the high-molecular-weight transport as passive transport through a large-pore system. The equivalent small-pore radius was 5.0 nm, with a distribution of 150 pores per alveolus. The equivalent large-pore radius was 17.0 nm, with a distribution of one pore per seven alveoli. The small-pore fluid conductivity (2 × 10−5ml · h−1 · cm−2 · mmHg−1) was 10-fold larger than that of the large-pore conductivity.

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Methanol‐to‐Olefins Reaction over Large‐Pore Zeolites: Impact of Pore Structure on Catalytic Performance

Chemie Ingenieur Technik ◽

10.1002/cite.202000174 ◽

2021 ◽

Author(s):

Sungsik Park ◽

Gakuji Sato ◽

Ryota Osuga ◽

Yong Wang ◽

Yoshihiro Kubota ◽

...

Keyword(s):

Pore Structure ◽

Catalytic Performance ◽

Large Pore ◽

Large Pore Zeolites

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Influence of mud filtrate on the pore system of different sandstone rocks

Journal of Petroleum Science and Engineering ◽

10.1016/j.petrol.2021.108595 ◽

2021 ◽

Vol 202 ◽

pp. 108595

Author(s):

Hany Gamal ◽

Salaheldin Elkatatny ◽

Abdulrauf Adebayo

Keyword(s):

Pore System ◽

Mud Filtrate

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Effect of freeze–thaw cycle on physical and mechanical properties and damage characteristics of sandstone

Scientific Reports ◽

10.1038/s41598-021-91842-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Longxiao Chen ◽

Kesheng Li ◽

Guilei Song ◽

Deng Zhang ◽

Chuanxiao Liu

Keyword(s):

Mechanical Properties ◽

Shear Failure ◽

Triaxial Compression ◽

Physical And Mechanical Properties ◽

Freeze Thaw ◽

Damage Characteristics ◽

Large Pore ◽

Natural Rock ◽

Thaw Cycle ◽

Freeze Thaw Cycle

AbstractRock deterioration under freeze–thaw cycles is a concern for in-service tunnel in cold regions. Previous studies focused on the change of rock mechanical properties under unidirectional stress, but the natural rock mass is under three dimensional stresses. This paper investigates influences of the number of freeze–thaw cycle on sandstone under low confining pressure. Twelve sandstone samples were tested subjected to triaxial compression. Additionally, the damage characteristics of sandstone internal microstructure were obtained by using acoustic emission (AE) and mercury intrusion porosimetry. Results indicated that the mechanical properties of sandstone were significantly reduced by freeze–thaw effect. Sandstone’ peak strength and elastic modulus were 7.28–37.96% and 6.38–40.87% less than for the control, respectively. The proportion of super-large pore and large pore in sandstone increased by 19.53–81.19%. We attributed the reduced sandstone’ mechanical properties to the degenerated sandstone microstructure, which, in turn, was associated with increased sandstone macropores. The macroscopic failure pattern of sandstone changed from splitting failure to shear failure with an increasing of freeze–thaw cycles. Moreover, the activity of AE signal increased at each stage, and the cumulative ringing count also showed upward trend with the increase of freeze–thaw number.

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