Osmotic Conductance of the Peritoneum in Capd Patients with Permanent Loss of Ultrafiltration Capacity

1996 ◽  
Vol 16 (5) ◽  
pp. 488-496 ◽  
Author(s):  
Jacek Waniewski ◽  
Olof Heimbürger ◽  
Andrzej Werynski ◽  
Bengt Lindholm
Keyword(s):  
Linear Relationship ◽  
Absorption Rate ◽  
Diffusion Rate ◽  
Solute Diffusion ◽  
Time Model ◽  
High Diffusion ◽  
High Diffusion Rate ◽  
Permanent Loss ◽  
The Difference ◽  
Dialysate Volume

Objective To compare the effectiveness of osmotic pressure in the induction of fluid flow during continuous ambulatory peritoneal dialysis (CAPD) in patients with permanent loss of ultrafiltration capacity (UFC) and clinically stable patients. Design Estimation of osmotic conductance in individual CAPD patients using data from single CAPD dwell studies. Patients Twenty clinically stable CAPD patients with normal ultrafiltration rate (NUR group); 8 CAPD patients with permanent UFC loss due to high diffusion rate for small solutes [high diffusion rate (HDR) group]; 3 CAPD patients with permanent loss of UFC dueto high absorption rate (HAR) of peritoneal dialysate (HAR group). Design Six-hour dwell studies were carried out in each patient using 2 L of Dianeal 3.86% dialysis fluid. Dialysate volume and the peritoneal absorption rate were measured using radioiodinated serum albumin as a marker. The dialysate volume over dwell-time curves were examined using three mathematical models of fluid transport for solutions with a crystalloid osmotic agent: model P, based on a phenomenologically derived exponential function of time; model OS, based on the linear relationship between the rate of net volume change (Qv) to the difference of osmolality in dialysate and blood; and model G, based on the linear relationship between Qv and the difference of glucose concentration in dialysate and blood. Results All three models provided an accurate description of the measured dialysate volume over time curves. The osmotic conductance, defined as the coefficient of proportionality between the rate of ultrafiltration and the osmolality (or, alternatively, glucose) gradient between dialysate and blood plasma, was 30% lower in the HDR group than in the NUR group, but close to the normal value in the HAR group. Conclusion In the HDR group the changes in the peritoneal membrane, which resulted in the increased diffusion rate of small solutes, also yielded a decrease of osmotic conductance. In contrast, the changes in the membrane in the HAR group, which resulted in increased peritoneal absorption, did not change the osmotic con ductance or the solute diffusion rate. The detailed pathophysiological mechanisms for these two different types of UFC loss failure are still unknown.

scholarly journals Improved impregnation efficiency and pulp yield of softwood kraft pulp by high effective alkali charge in the impregnation stage

Holzforschung ◽  
2016 ◽  
Vol 70 (11) ◽  
pp. 1031-1037 ◽  
Author(s):  
Elisabet Brännvall ◽  
Marie Bäckström
Keyword(s):  
Kraft Pulp ◽  
Yield Loss ◽  
Diffusion Rate ◽  
Pulp Yield ◽  
Yield Increase ◽  
High Diffusion ◽  
High Diffusion Rate ◽  
Rapid Loading ◽  
Softwood Kraft Pulp

Abstract A pulp yield increase up to 2% can be achieved by impregnation with a liquor containing 2 M effective alkali (EA) concentration instead of 1 M. The yield increase is due to higher cellulose and glucomannan contents in the pulp, which can be rationalized by less yield loss by peeling, as impregnation is more effective at an elevated EA level. A rapid loading of chips with alkali can be realized due to a high diffusion rate. When the temperature becomes higher in the cooking stage, enough alkali is available for delignification reactions without the risk of alkali depletion in the chip core, so that the delignification is more homogeneous.

Surface ligand-mediated isolated growth of Pt on Pd nanocubes for enhanced hydrogen evolution activity

2015 ◽  
Vol 3 (47) ◽  
pp. 23660-23663 ◽  
Author(s):  
Fumin Ren ◽  
Haiyuan Lu ◽  
Haotian Liu ◽  
Zheng Wang ◽  
Yuen Wu ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Diffusion Rate ◽  
Growth Mode ◽  
Island Growth ◽  
Mode Structure ◽  
High Diffusion ◽  
High Diffusion Rate ◽  
Layered Growth ◽  
Surface Ligand ◽  
Free Area

Br− ions can affect the growth mode of Pt on a Pd substrate. When Br− ions adsorb on some sites of the Pd cube, the newly formed Pt atoms tended to grow on the Br− free area, facilitating island growth mode. Otherwise, without Br− ions, because of the relatively high diffusion rate between Pt and Pd, Pt atoms can epitaxially deposit on the whole surface of the Pd nanocubes, forming a layered growth mode structure.

Nitrogen-Doped Graphene Nanoscroll Foam with High Diffusion Rate and Binding Affinity for Removal of Organic Pollutants

Small ◽  
2017 ◽  
Vol 13 (14) ◽  
pp. 1603779 ◽  
Author(s):  
Qile Fang ◽  
Xufeng Zhou ◽  
Wei Deng ◽  
Yuewen Liu ◽  
Zhi Zheng ◽  
...  
Keyword(s):  
Binding Affinity ◽  
Organic Pollutants ◽  
Diffusion Rate ◽  
Nitrogen Doped ◽  
High Diffusion ◽  
High Diffusion Rate ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

Simple Models for Fluid Transport during Peritoneal Dialysis

1996 ◽  
Vol 19 (8) ◽  
pp. 455-466 ◽  
Author(s):  
J. Waniewski ◽  
O. Heimbürger ◽  
A. Werynski ◽  
B. Lindholm
Keyword(s):  
Peritoneal Dialysis ◽  
Amino Acid ◽  
Linear Relationship ◽  
Fluid Transport ◽  
Good Description ◽  
Transport Coefficients ◽  
Osmotic Agent ◽  
The Difference ◽  
Dialysate Volume ◽  
Dialysis Fluids

Peritoneal fluid transport can be predicted using different simplified formulas. To evaluate three such models, fluid transport was studied in 38 single six hour dwell studies using standard glucose 1.36% (n=9), 2.27% (n=9) and 3.86% (n=20) dialysis fluids as well as amino acid 2.70% fluid (n=8) in 33 patients on continuous ambulatory peritoneal dialysis (CAPD). Dialysate volume and the peritoneal absorption rate were measured using radioiodinated serum albumin (RISA) as a marker. The dialysate volume over dwell time curves were examined using three mathematical models of fluid transport for solutions with a crystalloid osmotic agent: Model P based on phenomenologically derived exponential function of time (Pyle, 1981), Model OS based on linear relationship between the rate of net volume change, Qv, to the difference of osmolality in dialysate and blood, and Model G based on linear relationship between Qv and the difference of glucose concentration in dialysate and blood. All these models provided a good description of the measured dialysate volume over time curves, however the descriptions with Models OS and G for glucose 3.86% fluid were slightly but significantly less precise. The coefficients of Model OS were stable in time, but the coefficients of Model G and P dependend in general on the time period used for their estimation, especially for glucose 3.86% dialysis fluid. The evaluation of dwell studies with solutions containing amino acid 2.70% (instead of glucose) as osmotic agent, using Model OS and P, showed that the transport coefficients were stable in time and both models provided equally precise descriptions. These results suggested that all three models can be used but models P and OS can be preferred for pratical applications such as predictions of fluid transport with alternative cristalloid osmotic agents. Furthermore, we found that the peritoneal barrier for fluid transport may change transiently during exchanges with the standard glucose - based dialysis fuid, whereas such changes were not observed with the amino acid-based fluid. This discrepancy may be due to a different composition of the dialysis fluids, including osmotic agent, buffer and pH.

Oxygen-induced high diffusion rate of magnesium dopants in GaN/AlGaN based UV LED heterostructures

2018 ◽  
Vol 20 (20) ◽  
pp. 13890-13895 ◽  
Author(s):  
Paweł Piotr Michałowski ◽  
Sebastian Złotnik ◽  
Jakub Sitek ◽  
Krzysztof Rosiński ◽  
Mariusz Rudziński
Keyword(s):  
Diffusion Rate ◽  
Uv Led ◽  
High Diffusion ◽  
High Diffusion Rate

Oxygen breaks up Mg–H complexes and induces high diffusion of Mg in GaN/AlGaN heterostructures.

Annual differences in quality of leaf litter of aspen (Populus tremuloides) affecting rates of decomposition

1988 ◽  
Vol 66 (10) ◽  
pp. 1940-1947 ◽  
Author(s):  
Barry R. Taylor ◽  
Dennis Parkinson
Keyword(s):  
Water Absorption ◽  
Leaf Litter ◽  
Populus Tremuloides ◽  
Decomposition Rate ◽  
Rocky Mountains ◽  
Absorption Rate ◽  
Trembling Aspen ◽  
Leaching Loss ◽  
The Difference

Freshly fallen leaf litter was collected from a stand of trembling aspen (Populus tremuloides Michx.) in the Rocky Mountains of Alberta each autumn from 1981 through 1984. Leaves from 1981 and 1982 were yellow, waxy, and strong. Leaves from 1983 were pale brown and very brittle, and almost 1% of them suffered symmetrical deformities. Leaves from 1984 were composed of 80% yellow leaves and 20% green leaves, which apparently abscissed before senescence. Green and yellow 1984 leaves were distinctly different with respect to total (3 days) leaching loss, leachate conductivity, and proportions of ash, cellulose, and labile material. Green 1984 leaves contained twice as much nitrogen as yellow ones (13.1 vs. 6.5 mg∙g−1) and significantly more phosphorus (1.6 vs. 1.3 mg∙g−1). Leaves of different years varied widely with respect to leaf mass, water absorption rate, mass and conductivity of leachate, and proportions of cellulose, labiles, lignin, and ash, but there was no consistent ordering among years; leaves of different colouration (especially 1981 and 1983) were often physicochemically similar, while leaves identical in appearance were often chemically different. Small but significant differences in N and P concentrations among years were removed by 2 h leaching. Leaves of 1981 decomposing in laboratory microcosms at 26 °C lost less mass than either 1982 or 1983 leaves after 1 month, but not after 2 months. Ability of the cuticle to resist water absorption was probably responsible for the difference in initial decomposition rate.

Fluid and Solute Transport in CAPD Patients before and after Permanent Loss of Ultrafiltration Capacity

2005 ◽  
Vol 28 (10) ◽  
pp. 976-984 ◽  
Author(s):  
J. Waniewski ◽  
D. Sobiecka ◽  
M. DĘbowska ◽  
O. Heimbürger ◽  
A. Werynski ◽  
...  
Keyword(s):  
Solute Transport ◽  
Absorption Rate ◽  
Fluid Absorption ◽  
Transport Parameters ◽  
Normal Range ◽  
Peritoneal Transport ◽  
High K ◽  
Before And After ◽  
Permanent Loss ◽  
High Fluid

Background Two major types of permanent loss of ultrafiltration capacity (UFC) were previously distinguished among patients treated with CAPD: 1) type HDR with high diffusive peritoneal transport rate of small solutes and low osmotic conductance, but with normal fluid absorption rate, and 2) type HAR with high fluid absorption rate, but with normal diffusive peritoneal transport rate of small solutes and normal osmotic conductance. However, the detailed pattern of changes in peritoneal transport parameters in patients developing loss of ultrafiltration capacity is not known. Objective Analysis of solute and fluid transport parameters in the same patient before and after UFC loss. Patients Seven CAPD patients who had undergone repeated dwell studies, which were carried out before and/or after the onset of UFC loss. Methods Dialysis fluids (2 L) with glucose or a mixture of amino acids as osmotic agent at three basic tonicities were applied during 6 hour dwell studies. Fluid and solute transport parameters were previously shown not to be affected by these dialysis solutions (except by hypertonic amino acid-based solution). Intraperitoneal dialysate volume and fluid absorption rate were assessed using radiolabeled human serum albumin (RISA). Osmotic conductance (aOS) was estimated by a mathematical model as ultrafiltration rate induced by unit osmolality gradient. Diffusive mass transport coefficients, KBD, for glucose, urea, and creatinine were estimated using the modified Babb-Randerson-Farrell model. Results Five patients had increased KBD for small solutes after the onset of UFC loss, and three of them had decreased aOS, whereas two patients had normal aOS. In one of them, aOS decreased with time after the onset of UFC loss with concomitant normalization of glucose absorption. In all studies of these five patients the fluid absorption rate was within the normal range. Two other patients had increased fluid absorption rate (about 5 ml/min), and one of them also had increased KBD for small solutes, in two consecutive dwell studies in each patient with the second study being carried out at 1 and 7 months respectively after the first one. In all four studies in these two patients, the aOS was within the normal range. The sodium dip during dialysis with 3.86% glucose-based solution was lost, not only among most patients with UFC loss related to reduced osmotic conductance, but also in patients with increased KBD. Conclusions The occurrence of two major types of UFC loss was confirmed. However, a case of a mixed type of UFC loss with high fluid absorption rate and high KBD for small solutes, but normal osmotic conductance, and with normalization of initially high KBD for small solutes, linked with decreasing initially normal osmotic conductance, was also found. As a reduced sodium dip with hypertonic glucose solution is not only seen in patients with reduced osmotic conductance, it cannot reliably be used as a single measure of decreased aquaporin function. Permanent ultrafiltration capacity loss may be a dynamic phenomenon with a variety of alterations in peritoneal transport characteristics.

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