High Tw Research Articles

A multivariate piecewise interpolation model for viscosity representation and its application to the numerical simulation of non-isothermal polymer melt flow

In this study, a multivariate piecewise interpolation model is introduced to represent melt viscosity based on temperature and shear rate. The model does not require a predefined functional form for the entire data range, instead finding a suitable line between adjacent measured viscosity data points to obtain viscosity as a function of shear rate and temperature. To assess the effect of viscosity representation on polymer melt flow, a two-dimensional (2D) flow past a cylinder problem and a three-dimensional (3D) single screw extruder problem are numerically solved using different viscosity models. The pressure drop (ΔP) from the shift-factor model deviates by more than 10% at an average velocity (Uav) of 1 m/s due to overestimation of viscosity in the high shear rate region. The dimensionless thicknesses of the thermal boundary layer near the channel wall (δT/H) at wall temperature (Tw) of 210 °C are also misevaluated by more than 4% using both the shift-factor model and the Klein model, reflecting their poor viscosity evaluation. It is noteworthy that in all viscosity models, a high Tw leads to the formation of a thin thermal boundary layer, which adversely affects the heat transfer. In single screw extruder applications, viscosity misevaluation in high shear rate regions causes issues in pure drag flow cases, while misevaluation in low shear rate regions causes issues in pure back-pressure flow cases. These analyses highlight the accuracy and versatility of our multivariate piecewise interpolation model compared to existing viscosity models.

Anthropogenic Climate Change and Urbanization Exacerbate Risk of Hybrid Heat Extremes in China

AbstractDry‐ and wet‐bulb temperature (Td and Tw) are usually to define heatwaves (HWs) which have been enhanced under anthropogenic climate change (ACC) and urbanization. However, responses of various types of HWs (i.e., dry HWs, only high Td; humid HWs, only high Tw; hybrid HWs, both high Td and Tw; total HWs, high Td or Tw), to ACC and urbanization remain unknown. In this study, both observations and simulations show significantly increasing occurrence probability of total HWs over China during 1971–2020, whereas this increase is mainly reflected in hybrid HWs, followed by dry HWs and humid HWs. 68.2%–93.0% of the observed increases in the above four types of HWs can be attributed to ACC; on the other hand, urbanization tends to suppress humid HWs but enhance dry HWs, as a result of contributing to the increase of hybrid HWs by 10.9%. Under future ACC, total HWs are projected to be more frequent as expected, which is mainly sourced from the increasing hybrid HWs because dry/humid HWs are projected to be steady/downward. As a consequence, urban population exposure to ACC‐induced total HWs would remarkably increase to 83.55 billion person‐days by the 2090s, 89.5% of which can be attributed to hybrid HWs. Urbanization would amplify this population exposure of ACC‐induced hybrid HWs from 74.79 billion person‐days to 110.9 billion person‐days. Our results underscore the importance of improving understanding of hybrid HWs in urban areas and developing targeted adaptation planning on a warmer planet.

Evaluating Ion Accumulation and Storage in Traveling Wave Based Structures for Lossless Ion Manipulations.

Structures for lossless ion manipulations (SLIM) technology has demonstrated high resolving power ion mobility separation and flexibility to integrate complex ion manipulations into a single experimental platform. To enable IMS separations, trapping/accumulating ions inside SLIM (or in-SLIM) prior to injection of a packet for separations provides ease of operation and reduces the need for dedicated ion traps external to SLIM. To fully characterize the ion accumulation process, we have evaluated the effect of TW amplitudes, ion collection times, and storage times on the "in-SLIM" accumulation process. The study utilized a SLIM module comprising 5 distinct tracks, each with a specific ion accumulation configuration. The effect of the TW conditions on the accumulation process was investigated for a 3-peptide mixture: kemptide, angiotensin II, and neurotensin at a TW speed of 106 m/s. The effect of ion accumulation time/collection time and storage time was investigated, in addition to TW amplitude. Overall, the signal of the analyte ions increased when the ion collection time increased from 49 to 163 ms but decreased when the ion collection time increased further to 652 ms due to the space charge effects. Ion losses were observed at high TW amplitudes (e.g., 15 Vp-p and 20 Vp-p). In addition, under space charge conditions (e.g., collection times of 163 and 652 ms), the signal of the analyte ions decreased with an increase in storage times for all TW amplitudes applied to the trapping region. For ion accumulation, the data indicate that gentler TW conditions must be utilized to minimize ion losses and fragments to benefit from the "in-SLIM" accumulation process. Wider SLIM tracks provided better performance than those with narrower tracks.

Regimes of Soil Moisture–Wet-Bulb Temperature Coupling with Relevance to Moist Heat Stress

Abstract Human heat stress depends jointly on atmospheric temperature and humidity. Wetter soils reduce temperature but also raise humidity, making the collective impact on heat stress unclear. To better understand these interactions, we use ERA5 to examine the coupling between daily average soil moisture and wet-bulb temperature (Tw) and its seasonal and diurnal cycle at global scale. We identify a global soil moisture–Tw coupling pattern with both widespread negative and positive correlations in contrast to the well-established cooling effect of wet soil on dry-bulb temperature. Regions showing positive correlations closely resemble previously identified land–atmosphere coupling hotspots where soil moisture effectively controls surface energy partition. Soil moisture–Tw coupling varies seasonally closely tied to monsoon development, and the positive coupling is slightly stronger and more widespread during nighttime. Local-scale analysis demonstrates a nonlinear structure of soil moisture–Tw coupling with stronger coupling under relatively dry soils. Hot days with high Tw values show wetter-than-normal soil, anomalous high latent and low sensible heat flux from a cooler surface, and a shallower boundary layer. This supports the hypothesis that wetter soil increases Tw by concentrating surface moist enthalpy flux within a shallower boundary layer and reducing free-troposphere-air entrainment. We identify areas of particular interest for future studies on the physical mechanisms of soil moisture–heat stress coupling. Our findings suggest that increasing soil moisture might amplify heat stress over large portions of the world including several densely populated areas. These results also raise questions about the effectiveness of evaporative cooling strategies in ameliorating urban heat stress. Significance Statement The purpose of this study is to provide a global picture of the relationship between soil moisture anomalies and a heat stress metric that includes the joint effects of temperature and humidity. This is important because a better understanding of this relationship will help improve the prediction of extreme heat stress events and inform strategies for ameliorating heat stress. We find a widespread positive correlation between soil moisture and heat stress, in contrast to studies relying on temperature alone. This raises the possibility that, over much of the world, and in the most populous regions, strategies like irrigation or “greening” that can reduce temperature might be ineffective or even harmful in reducing heat stress with humidity incorporated.

Drought impacts on river water temperature: A process‐based understanding from temperate climates

AbstractHigh river water temperature (Tw) extremes have been widely reported during drought conditions as extreme low‐flows often coincide with high atmospheric energy inputs. This has significant implications for freshwater ecosystem health and sustainable river management practices globally. However, the extent to which different meteorological and hydrological processes interact during droughts to govern Tw dynamics, and how this varies between environmental contexts, remains poorly understood. Here, we review the mechanisms controlling Tw dynamics during droughts across temperate, maritime environments, using the United Kingdom as a detailed case study. We evidence that Tw spikes have widely occurred during extreme low‐flow events observed within droughts, but such trends have been inconsistent due to varying hydroclimatic conditions and river basin controls. To better understand this, we re‐conceptualize the mechanisms governing drought‐induced Tw dynamics operating across three ‘process sets’: (i) ‘energy flux dynamics’ as non‐advective controls on Tw; (ii) the role of ‘reach‐scale habitat conditions’ in mediating non‐advective controls on Tw, including hydraulic properties (e.g., residence time) and physical conditions (e.g., riparian vegetation coverages, wetted perimeters); (iii) ‘water source contributions’ (surface water and groundwater) as advective heat and water flow controls. We review natural and anthropogenic influences affecting Tw controls within each process set and discuss how such mechanisms are likely to change under drought conditions. More systematic research (spanning various river environments and drought severities) is required to test such concepts, with existing scientific knowledge on drought‐induced Tw dynamics being largely gleaned from studies examining non‐extreme low‐flow conditions or with broader focuses (e.g., annual thermal dynamics). We conclude by highlighting critical future research questions that need to be answered to better model Tw dynamics during future droughts and for unmonitored sites. Such scientific advances would more effectively inform how high Tw extremes could be better managed through evidence‐based mitigation and adaptation strategies.

Interfacial heat transfer and boiling transition of the droplets on superheated surface with Leidenfrost effects

This study, a novel three-dimensional (3D) method is developed to address the Leidenfrost effect issues with a focus on the synergies of droplet velocity (v) and surface temperature (Tw). Here, we proposed a 3D computational fluid dynamics numerical simulation that combines a VOF model and an amended evaporation model and performed high-speed video testing for capturing vapor dynamics details and distinguish anisotropic heat transfer on a high-temperature surface near the Leidenfrost point. The results revealed that the law of the dynamic Leidenfrost point (TDLT) was predominated by changes in the thickness and shape of the vapor layer. Additionally, coexistence of v and Tw produced a vapor layer, instantly disentangling the boiling state and initiating a gradual change from contact boiling to film boiling, with v affecting the boiling state transition and delaying buildup of the vapor layer aggregation. We determined the empirical correlation of TDLT with the Weber number (We) as follows: TDLT=376.65+84.45×We0.22. Moreover, the high Tw promoted vapor layer formation, thereby decreasing the heat transfer efficiency, whereas the large v inhibited vapor layer formation and enhanced interfacial heat transfer. These findings contribute to a better understanding of the theoretical basis for inhibiting the Leidenfrost effect.

Ignition predictions of isolated coal particles by different ignition criteria and devolatilization models

The prediction accuracy of coal ignition characteristics depends on the sub-model selections. A detailed modeling study on the influences of ignition criteria and devolatilization models on the ignition characteristics of isolated coal particles is conducted using a one-dimensional transient ignition model. The assessed ignition criteria include the thermal explosion theory (TET), the transient adiabatic criterion (TAC) and the flammability limit criterion (FLC), while the assessed the devolatilization models include the chemical percolation devolatilization (CPD) one and two competing reaction (TCR) one. Under each combination, the ignition characteristics under different oxygen concentration, particle size, and surrounding temperature are studied. The prediction results are compared with microgravity experimental data obtained from the 3.6 s drop tower in National Microgravity Laboratory Center of China (NMLC). Modeling results reveal that the particle center temperature is more reasonable to be used as the characteristic temperature in the ignition study. When devolatilization process is described by CPD model, for homogenous ignition FLC is more accurate to predict ignition temperature and time than TAC at a higher XO2 and a high Tw, while TAC is more accurate to predict ignition temperature at a large particle size. Using FLC, against TAC, the transient of ignition mode from homogenous to combined happens at a ∼ 80 K higher temperature and ∼ 50 μm larger particle size, while that from combined to heterogenous happens at 250 μm rather than 400 μm. When FLC is used as the ignition criterion, selection of devolatilization model has more notable effect on the prediction of ignition temperature and time. Furthermore, the combination of FLC and CPD is more accurate to predict ignition temperature and time at a higher XO2. Two diagrams are respectively given to guide the selection the ignition criterion and identify the ignition mode at a wide range of conditions. In addition, the mechanisms of the associated discrepancy are discussed.

Effects of Hot Wire Temperature on Properties of GeSi:H Films with High Hydrogen Dilution by Hot-Wire Chemical Vapor Deposition

GeSi:H films are prepared by hot-wire chemical vapor deposition (CVD) with high hydrogen dilution, DH=98%. Effects of hot wire temperature (Tw) on deposition rate, structural properties and bandgap of GeSi:H films are studied with surface profilemeter, Raman spectroscopy, Fourier transformed infrared spectroscopy, and UV-VIS-NIR spectrophotometer. It is found that the deposition rate (Rd) goes up with increasing of Tw, but increasing rate of Rd declines when Tw⩾1 550 °C. High Tw is beneficial to the formation of Ge-Si, but it has little effect on relative contents of the hydrogen bonds (Ge-H, Si-H, etc.) in the films. In the Tw range of 1 400–1 850 °C, the maximum bandgap of the GeSi:H films is 1.39 eV at Tw =1 450 °C and the band gap decreases with Tw increasing when Tw⩾1 450 °C.

Characterization of Extreme Wet‐Bulb Temperature Events in Southern Pakistan

AbstractWe study extreme wet‐bulb temperature (Tw) events in a regional hot spot of high Tw values in southwest Pakistan's Indus Valley. We focus on the May–June premonsoon months and employ a combination of station data, ERA‐Interim reanalysis, and trajectory calculations to analyze the extreme events. We find that the events are associated with anomalous influx of marine air from the Arabian Sea. The air flows in a shallow layer below 950 hPa and is heated and moistened by diabatic processes over land, arriving at the hot spot region with very high Tw. We surmise that surface evaporation within the strip of well‐irrigated land flanking the Indus River plays a major role in generating these extreme Tw values. Our results imply that studies of extreme Tw events in future, warmer climates must pay close attention to fine‐scale diabatic processes within the boundary layer, especially evaporation over land.

The Role of Environmental Variables on Distribution of Potamogetonaceae Species

Potamogetonaceae is one of the most diverse aquatic plant families in the world and in Turkey. No research has been done on environmental preferences of Potamogetonaceae species in Turkey. We aimed to understand the relationship between distribution of species and hydrochemistry using canonical correspondence analysis. Distribution and abundance patterns of species along an altitudinal gradient were also investigated. We collected 14 Potamogetonaceae species from 96 wetlands throughout Turkey and measured 10 water chemistry parameters. The most important environmental variables were electrical conductivity (EC), water temperature (Tw), dissolved oxygen (DO), and pH. These variables explained 5.9% of the total variance. Potamogeton coloratus had the lowest Tw and pH and the highest EC optima. Potamogeton gramineus preferred high Tw and pH and the lowest EC. Stuckenia amblyphylla had high DO and low Tw and EC preferences. Potamogeton natans sampled from highlands had the lowest DO optima. Stuckenia pectinata had the highest tolerance for EC and, along with P. crispus, the highest Tw tolerance. Remaining species are widespread with broad altitudinal distributions and average values of environmental parameters. The most vulnerable species are P. coloratus, S. amblyphylla and P. gramineus as they have special habitat preferences and narrow tolerances.

Energy Retrofits in Multi-family Buildings in North-east Europe: The Impacts on Thermal Conditions

We have conducted a project to develop a common protocol for indoor environmental quality (IEQ) assessment and to assess the effects of energy retrofits on IEQ. This paper focuses on thermal comfort, which was first assessed based on 2-month continuous monitoring in 16 multi-family buildings (94 apartments) in Finland and 20 buildings (96 apartments) in Lithuania during heating season before retrofits. In addition, corresponding data after retrofits were available from three buildings (17 apartments) from Finland and seven (30 apartments) from Lithuania. Two data loggers per apartment were placed to evaluate Tw and RHw (warm area), and Tc and RHc (coldest spot). Questionnaire data regarding housing quality and health were collected from the occupants. The results before retrofits indicated high Tw (>23°C) for a large proportion of time in Finnish apartments, whereas opposite trend was observed in Lithuania. After retrofits, proportion of time with high Tw was higher while proportion of apartments with low RHw was lower in Finland, whereas in Lithuania, about one fourth of the apartments had higher Tw and RHw, hence fulfilling the national guidelines. The average absolute humidity was higher after retrofits in both countries, especially in Lithuania (by 15%). Occupant responses indicated improved thermal comfort. Therefore, potential effects of energy retrofits on occupants’ thermal environment and satisfaction were demonstrated, and simply adjusting indoor temperature could help to save energy. Further analysis is needed to include the effects of outdoor conditions, as well as overall IEQ to the assessment.

Genotypic variation in the response to high water temperature during vegetative growth and the effects on rice productivity under a cool climate

We examined the effects of high water temperature (Tw) during early vegetative growth on dry matter production, grain yield, and grain quality in a 2-year field trial in northern Japan using two rice cultivars: ‘Hitomebore’, a standard cultivar for this region, and ‘Koshihikari’, a late-maturing cultivar. The heading date of ‘Koshihikari’ was 8–9 days later than that of ‘Hitomebore’. Heading date was significantly earlier for both cultivars (by 2–5 days) in the high Tw treatment, without a significant cultivar×Tw interaction. High Tw significantly increased dry matter production before heading, and there was a significant cultivar×Tw interaction: ‘Koshihikari’ responded more than ‘Hitomebore’ to high Tw. This genotypic difference was explained by the daily rate of dry matter increase rather than by the growth duration. After heading, leaf senescence measured as the reduction of the SPAD value was greater at high Tw for both cultivars. Radiation-use efficiency after heading was significantly reduced by high Tw for both cultivars. Consequently, the positive effect of high Tw on dry matter production was reduced for both cultivars at harvest. Grain yield was significantly increased by high Tw (by 1–20%), but without a significant Tw×cultivar interaction. These results suggest that to increase grain yield above that for the standard cultivar ‘Hitomebore’, manipulation of the accelerated leaf senescence caused by high Tw will be a key factor in efforts to adapt rice to future global warming.

Genotypic Variation in Rice Cold Tolerance Responses during Reproductive Growth as a Function of Water Temperature during Vegetative Growth

We examined genotypic variation in the effect of rice (Oryza sativa L.) responses to water temperature (Tw) during vegetative growth on cold tolerance during reproductive growth in pot and field experiments. Cold tolerance was evaluated based on the percentage spikelet sterility induced by a cool and deep irrigation treatment during the reproductive growth phases. In the pot experiment, rice plants from two cultivars with different cold tolerance were exposed to different levels of Tw during vegetative growth and their cold tolerance was tested. Spikelet sterility of both cultivars decreased with increasing Tw during the vegetative growth phase for temperatures ranging from 19 to 30°C, with parallel lines for the regression equations for sterility as a function of temperature (a slope of 4.0% per 1°C) for both cultivars, although the y‐intercepts differed by 38% points between the cultivars. In the field experiment, four rice cultivars were grown under two levels of Tw during vegetative growth, and their cold tolerance was tested during reproductive growth at two locations (Miyagi Prefecture and Aomori Prefecture in Japan). We found that spikelet sterility decreased at high Tw during vegetative growth for all cultivars and locations. Our results suggest that high Tw during vegetative growth can improve cold tolerance during reproductive growth for the tested cultivars without a significant cultivar × Tw interaction.

Specificity of Markers of Leukemia Initiating Cells with a New Multiparameter Flow Cytometry Based Appraoch; Impact for Prognostic and Therapeutic Applications

AbstractAbstract 1834Leukemia stem cells (LSC) are proposed to underly relapse of AML. In order to develop methods to specifically detect LSCs and to design LSC specific therapies, discrimination between LSC and normal hematopoietic stem cells (HSC) is a prerequisite. HSC and LSC may be either CD34-positive (CD34+CD38-) or CD34-negative. The latter may be contained in stem cell compartments defined by functional parameters: Hoechst 33342 efflux (side population, SP) and ALDH activity. To discriminate between LSCs and HSCs aberrant cell surface markers have been described. Additional flowcytometric parameters (scatter, and level of expression of CD34/CD45) allow further discrimination (Terwijn Blood 2009; 114:165). We applied this new approach to compare the specificity of expression of the LSC markers CD123, CLL-1, CD96, CD44, CD47, and CD33. We studied LSCs in diagnosis AML, HSCs in normal bone marrow (NBM) and regenerating BM (RBM) and HSCs present at diagnosis in the AML BM itself. The Table shows the results for the CD34+CD38-cells. Large differences were found for LSCs: CD44>CD33>CD47>CD123≥CLL-1 and CD96 (column 2; median and ranges shown in all columns). Expression on HSCs in NBM (column 4) shows the lack of LSC specificity of several of these markers: CD44>CD47>CD33>CD123>CD96 and CLL-1. A similar result was found for RBM for the three markers studied: CD33>CD123>CLL-1 (column 5). Expression in HSCs present in the AML BM itself was: CD33>CD123>CLL-1 and CD96 (column 3). CD44 and CD47 could not be properly analyzed due to extensive overlap of LSC and HSC (column 3). In order to determine whether expression on HSC would negatively impact diagnostic and targeted therapy, we defined an in vitro “therapeutic window” (TW=expr. in LSC/expr. in HSC) in columns 6–8: each individual value for LSC for a particular marker was divided by the median value of HSC in NBM (column 7), RBM (column 8) or divided by each corresponding HSC value in the AML BM itself (column 6). Overall, TW was slightly higher for CLL-1 than for CD96, CD123 and CD33, irrespective HSC source (CD33 had a high TW in diagnosis BM). The TW for CD44 and CD47 was low (column 7) and not analyzable in the AML BM itself. Experiments were repeated for SP cells: TW for CLL-1 (for the 3 HSC sources, resp) were 2.1, 3.8, and 3.8; for CD123: 2.0, 1.5, and 2.5 and for CD33: 1.9, 1.3, and 1.6. CLL-1 was thus slightly superior for SPs. The overall conclusions from this project are that, due to a high specificity, CD123, CLL-1, CD96 and CD33, but not CD44 and CD47 are suitable for diagnostic purposes. Whether or not a similar conclusion can be drawn for therapeutic applications remains to be investigated. Large differences exist in expression of the different antigens for most individual AML cases; for therapeutic applications, for each AML case, the optimal antigen or, most likely, combinations of antigens will be needed. The most important conclusion is that, by using our approach, it is now possible to discriminate between concomitantly present LSCs and HSCs. This approach may have high impact for both prognostic purposes (e.g. prediction of relapse) and prospective isolation of LSC and HSC from the same AML BM to design new therapeutic modalities. It may further serve as a surrogate marker to monitor effectiveness of a treatment and to design antibody/ligand combination therapies in a personalized setting. Disclosures:No relevant conflicts of interest to declare.

Surface properties of disordered γ MnO2 at the solid-electrolyte interface.

ABSTRACTRelationships between lattice parameters of manganese dioxides (γ/ε-MD) and their surface properties at the solid-aqueous solution interface were investigated. The studied series ranged from orthorhombic ramsdellite to tetragonal pyrolusite and encompassed disordered MD samples. The structural model used takes into account two structural defects which affect the orthorhombic network of ramsdellite: Pr (rate of pyrolusite intergrowth) and Tw (rate of microtwinning). Water adsorption isotherms showed that the cross sectional surface area of water molecules is linearly correlated to Pr: from 6.3 Å2 (Pr=0.2) to 13.1 Å2 (Pr=1). Titration of their surface charge evidenced a linear relationship between PZC and Pr starting from ramsdellite (Pr = 0, Tw = 0, PZC = 1) to pyrolusite (Pr = 1, Tw = 0, PZC = 7.3). γ-MD with intermediate values of Pr (0.2 to 0.45) have increasing PZC values. For similar Pr values (0.45), high Tw percentage (0.3 and 1) makes the PZC to increase. The experimental results are compared with data collected in the literature for dioxides of transition elements with tetragonal structure. Surface titration leads to the determination of electrochemically active surface area at alkaline pH.

Si-H Vibration Only at 2000 CM-1 in Fully Polycrystalline Silicon Films Made by Hwcvd

ABSTRACTThe Si-H vibration in IR spectra of our device quality poly-Si films grown by hot-wire chemical vapour deposition (HWCVD) made at low wire temperature (Tw=1800 °C) is at 2000 cm−1 whereas in a poly-Si film made at high wire temperature (Tw=1900 °C) both 2000 cm−1 vibrations as well as 2100 cm−1 are observed. On the other hand, the Raman spectra (probing the upper part of the film) of Si-H stretching vibration measured for both these samples show only 2000 cm-1 mode. XTEM micrographs of these films show that whereas the low Tw film has a structure made of closely packed crystalline columns, the high Tw film has conical crystalline structures with amorphous region between them. The crystal cones meet each other towards the top of the film and form a closed structure. This is confirmed by Raman spectrum at 520 cm−1. We attribute the 2100 cm−1 mode to the Si-H bonds at the surface of the cones touching the amorphous regions. The Si-H vibration shifts to 2000 cm-1 when the crystalline cones coalesce with each other, as is the case in the upper part of both types of films.

Discussion and Closure: New Approach to Design of Culverts

The tests conducted by the author cover two types of culvert flow, both with inlet control. The first has an unsubmerged inlet in which the upstream head is less than about 1.3 D and the second has a submerged inlet but a free outlet, with air access from downstream. The culvert used by the author in his tests is rather short, less than 20 pipe diameters, so that in this case there is no question of outlet control unless a high TW level is present. The 1:40 barrel slope seems to have been chosen to ensure supercritical flow in the barrel. The author suggests two empirical equations for the case where HId is less or greater than 1.28. Eqs. (3) and (4) can be put in the form

Skeletal muscle water and electrolytes in chronic renal failure. Effects of long-term regular dialysis treatment.

Skeletal muscle water, Cl, Na and K were studied in 24 patients with predialysis chronic renal failure (CRF) and in 16 patients under regular dialysis treatment (RDT) for 8-16 years; 35 healthy controls were also examined. Total Cl, Na and water (Clm, Nam, TW) were high in both CRF and RDT groups (p less than 0.001); high TW in CRF was due to both extra (ECW) and intracellular (ICW) fractions, which were calculated from Cl space; in RDT only ECW was increased and ICW was normal. Muscle K was diminished in CRF, in reference to both muscle fat free dry solids and ICW, and it was slightly but significantly higher than normal in RDT. The findings demonstrate that high cell volume and low intracellular K observed in CRF are fully corrected by long-term hemodialysis, probably because these abnormalities are mainly related to cell function disturbances due to uremic state. On the contrary, the persistence of high total Cl, Na and muscle ECW seems to be an expression of expanded extracellular fluid volume.