The immiscibility induced phase separation (I...PS) process was introduced as a novel method to fabricate hollow fibers with exceptionally high water permeance and reasonably high water/ethanol ...selectivity in dehydration of ethanol by pervaporation. As a continuation of the previous work, this study discloses the mechanisms to enhance the performance of hollow fibers spun via I...PS by elucidating the material selection at the inner-layer. Moreover, it revealed the methods to reduce mass-transport resistance by enhancing surface porosity for both inner and outer surfaces to further improve the permeation flux of the membranes. The continuous performance test demonstrates that the fibers spun from the I...PS possess a stable dehydration performance throughout the monitored period of 300 h. A comparison with pervaporation membranes in the literatures verifies the superiority of the membranes spun via I...PS process with the highest water permeation flux of 9.5 kg/m2 h and the permeate water purity of 95.8 wt % at 80...C. (ProQuest: ... denotes formulae/symbols omitted.)
Water-loss dehydration and aging Hooper, Lee; Bunn, Diane; Jimoh, Florence O. ...
Mechanisms of ageing and development,
03/2014, Letnik:
136-137
Journal Article
Recenzirano
Odprti dostop
•Twenty to 30% of older people have water-loss dehydration.•Dehydration is associated with increased mortality, morbidity and disability.•Vulnerability to dehydration is associated with ...aging.•Relationships between fluid intake and hydration status will be examined in NU-AGE.•NU-AGE will describe drinking and dietary patterns associated with good hydration.
This review defines water-loss and salt-loss dehydration. For older people serum osmolality appears the most appropriate gold standard for diagnosis of water-loss dehydration, but clear signs of early dehydration have not been developed. In older adults, lower muscle mass, reduced kidney function, physical and cognitive disabilities, blunted thirst, and polypharmacy all increase dehydration risk. Cross-sectional studies suggest a water-loss dehydration prevalence of 20–30% in this population. Water-loss dehydration is associated with higher mortality, morbidity and disability in older people, but evidence is still needed that this relationship is causal. There are a variety of ways we may be able to help older people reduce their risk of dehydration by recognising that they are not drinking enough, and being helped to drink more. Strategies to increase fluid intake in residential care homes include identifying and overcoming individual and institutional barriers to drinking, such as being worried about not reaching the toilet in time, physical inability to make or to reach drinks, and reduced social drinking and drinking pleasure. Research needs are discussed, some of which will be addressed by the FP7-funded NU-AGE (New dietary strategies addressing the specific needs of elderly population for a healthy ageing in Europe) trial.
BACKGROUND: Well-recognized markers for static (one time) or dynamic (monitoring over time) dehydration assessment have not been rigorously tested for their usefulness in clinical, military, and ...sports medicine communities. OBJECTIVE: This study evaluated the components of biological variation and the accuracy of potential markers in plasma, urine, saliva, and body mass (Bm) for static and dynamic dehydration assessment. DESIGN: We studied 18 healthy volunteers (13 men and 5 women) while carefully controlling hydration and numerous preanalytic factors. Biological variation was determined over 3 consecutive days by using published methods. Atypical values based on statistical deviations from a homeostatic set point were examined. Measured deviations in body fluid were produced by using a separate, prospective dehydration experiment and evaluated by receiver operating characteristic (ROC) analysis to quantify diagnostic accuracy. RESULTS: All dehydration markers displayed substantial individuality and one-half of the dehydration markers displayed marked heterogeneity of intraindividual variation. Decision levels for all dehydration markers were within one SD of the ROC criterion values, and most levels were nearly identical to the prospective group means after volunteers were dehydrated by 1.8-7.0% of Bm. However, only plasma osmolality (Posm) showed statistical promise for use in the static dehydration assessment. A diagnostic decision level of 301 plusmn 5 mmol/kg was proposed. Reference change values of 9 mmol/kg (Posm), 0.010 urine specific gravity (Usg), and 2.5% change in Bm were also statistically valid for dynamic dehydration assessment at the 95% probability level. CONCLUSIONS: Posm is the only useful marker for static dehydration assessment. Posm, Usg, and Bm are valid markers in the setting of dynamic dehydration assessment.
Evaluating and testing hydration status is increasingly requested by rehabilitation, sport, military and performance-related activities. Besides commonly used biochemical hydration assessment markers ...within blood and urine, which have their advantages and limitations in collection and evaluating hydration status, there are other potential markers present within saliva, sweat or tear. This literature review focuses on body fluids saliva, sweat and tear compared to blood and urine regarding practicality and hydration status influenced by fluid restriction and/or physical activity. The selected articles included healthy subjects, biochemical hydration assessment markers and a well-described (de)hydration procedure. The included studies (n=16) revealed that the setting and the method of collecting respectively accessing body fluids are particularly important aspects to choose the optimal hydration marker. To obtain a sample of saliva is one of the simplest ways to collect body fluids. During exercise and heat exposures, saliva composition might be an effective index but seems to be highly variable. The collection of sweat is a more extensive and time-consuming technique making it more difficult to evaluate dehydration and to make a statement about the hydration status at a particular time. The collection procedure of tear fluid is easy to access and causes very little discomfort to the subject. Tear osmolarity increases with dehydration in parallel to alterations in plasma osmolality and urine-specific gravity. But at the individual level, its sensitivity has to be further determined.
Background: Dehydration appears prevalent, costly and associated with adverse outcomes. We sought to generate consensus on such key issues and elucidate need for further scientific enquiry.
Materials ...and methods: A modified Delphi process combined expert opinion and evidence appraisal. Twelve relevant experts addressed dehydration's definition, objective markers and impact on physiology and outcome.
Results: Fifteen consensus statements and seven research recommendations were generated. Key findings, evidenced in detail, were that there is no universally accepted definition for dehydration; hydration assessment is complex and requires combining physiological and laboratory variables; "dehydration" and "hypovolaemia" are incorrectly used interchangeably; abnormal hydration status includes relative and/or absolute abnormalities in body water and serum/plasma osmolality (pOsm); raised pOsm usually indicates dehydration; direct measurement of pOsm is the gold standard for determining dehydration; pOsm >300 and ≤280 mOsm/kg classifies a person as hyper or hypo-osmolar; outside extremes, signs of adult dehydration are subtle and unreliable; dehydration is common in hospitals and care homes and associated with poorer outcomes.
Discussion: Dehydration poses risk to public health. Dehydration is under-recognized and poorly managed in hospital and community-based care. Further research is required to improve assessment and management of dehydration and the authors have made recommendations to focus academic endeavours.
Key messages
Dehydration assessment is a major clinical challenge due to a complex, varying pathophysiology, non-specific clinical presentations and the lack of international consensus on definition and diagnosis.
Plasma osmolality represents a valuable, objective surrogate marker of hypertonic dehydration which is underutilized in clinical practice.
Dehydration is prevalent within the healthcare setting and in the community, and appears associated with increased morbidity and mortality.
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